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[PATCH v1 1/2] Report wait event for cost-based vacuum delay 248+ messages / 3 participants [nested] [flat]
* [PATCH v1 1/2] Report wait event for cost-based vacuum delay @ 2020-03-21 01:47 Justin Pryzby <[email protected]> 0 siblings, 0 replies; 248+ messages in thread From: Justin Pryzby @ 2020-03-21 01:47 UTC (permalink / raw) --- doc/src/sgml/monitoring.sgml | 2 ++ src/backend/commands/vacuum.c | 2 ++ src/backend/postmaster/pgstat.c | 3 +++ src/include/pgstat.h | 3 ++- 4 files changed, 9 insertions(+), 1 deletion(-) diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml index 5bffdcce10..46c99a55b7 100644 --- a/doc/src/sgml/monitoring.sgml +++ b/doc/src/sgml/monitoring.sgml @@ -1507,6 +1507,8 @@ postgres 27093 0.0 0.0 30096 2752 ? Ss 11:34 0:00 postgres: ser (<filename>pg_wal</filename>, archive or stream) before trying again to retrieve WAL data, at recovery. </entry> + <entry><literal>VacuumDelay</literal></entry> + <entry>Waiting in a cost-based vacuum delay point.</entry> </row> <row> <entry morerows="68"><literal>IO</literal></entry> diff --git a/src/backend/commands/vacuum.c b/src/backend/commands/vacuum.c index d625d17bf4..59731d687f 100644 --- a/src/backend/commands/vacuum.c +++ b/src/backend/commands/vacuum.c @@ -2019,7 +2019,9 @@ vacuum_delay_point(void) if (msec > VacuumCostDelay * 4) msec = VacuumCostDelay * 4; + pgstat_report_wait_start(WAIT_EVENT_VACUUM_DELAY); pg_usleep((long) (msec * 1000)); + pgstat_report_wait_end(); VacuumCostBalance = 0; diff --git a/src/backend/postmaster/pgstat.c b/src/backend/postmaster/pgstat.c index d29c211a76..742ec07b59 100644 --- a/src/backend/postmaster/pgstat.c +++ b/src/backend/postmaster/pgstat.c @@ -3824,6 +3824,9 @@ pgstat_get_wait_timeout(WaitEventTimeout w) case WAIT_EVENT_RECOVERY_RETRIEVE_RETRY_INTERVAL: event_name = "RecoveryRetrieveRetryInterval"; break; + case WAIT_EVENT_VACUUM_DELAY: + event_name = "VacuumDelay"; + break; /* no default case, so that compiler will warn */ } diff --git a/src/include/pgstat.h b/src/include/pgstat.h index 851d0a7246..4db40e23cc 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -848,7 +848,8 @@ typedef enum WAIT_EVENT_BASE_BACKUP_THROTTLE = PG_WAIT_TIMEOUT, WAIT_EVENT_PG_SLEEP, WAIT_EVENT_RECOVERY_APPLY_DELAY, - WAIT_EVENT_RECOVERY_RETRIEVE_RETRY_INTERVAL + WAIT_EVENT_RECOVERY_RETRIEVE_RETRY_INTERVAL, + WAIT_EVENT_VACUUM_DELAY, } WaitEventTimeout; /* ---------- -- 2.17.0 --9jxsPFA5p3P2qPhR Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v1-0002-vacuum-to-report-time-spent-in-cost-based-delay.patch" ^ permalink raw reply [nested|flat] 248+ messages in thread
* [PATCH v2 5/6] Handle pg_get_expr default args in system_functions.sql @ 2025-12-09 19:17 Mark Wong <[email protected]> 0 siblings, 0 replies; 248+ messages in thread From: Mark Wong @ 2025-12-09 19:17 UTC (permalink / raw) Modernize pg_get_expr to use CREATE OR REPLACE FUNCTION to handle the optional pretty argument. --- src/backend/catalog/system_functions.sql | 7 +++++++ src/backend/commands/tablecmds.c | 4 ++-- src/backend/utils/adt/ruleutils.c | 17 ----------------- src/include/catalog/pg_proc.dat | 5 +---- 4 files changed, 10 insertions(+), 23 deletions(-) diff --git a/src/backend/catalog/system_functions.sql b/src/backend/catalog/system_functions.sql index 1824faab231..a6f7cdf3a36 100644 --- a/src/backend/catalog/system_functions.sql +++ b/src/backend/catalog/system_functions.sql @@ -692,6 +692,13 @@ LANGUAGE INTERNAL PARALLEL SAFE AS 'pg_get_constraintdef'; +CREATE OR REPLACE FUNCTION + pg_get_expr(expr pg_node_tree, relation oid, pretty bool DEFAULT false) +RETURNS TEXT +LANGUAGE INTERNAL +PARALLEL SAFE +AS 'pg_get_expr'; + -- -- The default permissions for functions mean that anyone can execute them. -- A number of functions shouldn't be executable by just anyone, but rather diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..12c4ce08437 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -17480,8 +17480,8 @@ decompile_conbin(HeapTuple contup, TupleDesc tupdesc) if (isnull) elog(ERROR, "null conbin for constraint %u", con->oid); - expr = DirectFunctionCall2(pg_get_expr, attr, - ObjectIdGetDatum(con->conrelid)); + expr = DirectFunctionCall3(pg_get_expr, attr, + ObjectIdGetDatum(con->conrelid), false); return TextDatumGetCString(expr); } diff --git a/src/backend/utils/adt/ruleutils.c b/src/backend/utils/adt/ruleutils.c index 9faf340f0c6..305e3e80c41 100644 --- a/src/backend/utils/adt/ruleutils.c +++ b/src/backend/utils/adt/ruleutils.c @@ -2573,23 +2573,6 @@ decompile_column_index_array(Datum column_index_array, Oid relId, */ Datum pg_get_expr(PG_FUNCTION_ARGS) -{ - text *expr = PG_GETARG_TEXT_PP(0); - Oid relid = PG_GETARG_OID(1); - text *result; - int prettyFlags; - - prettyFlags = PRETTYFLAG_INDENT; - - result = pg_get_expr_worker(expr, relid, prettyFlags); - if (result) - PG_RETURN_TEXT_P(result); - else - PG_RETURN_NULL(); -} - -Datum -pg_get_expr_ext(PG_FUNCTION_ARGS) { text *expr = PG_GETARG_TEXT_PP(0); Oid relid = PG_GETARG_OID(1); diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat index 96eb7baf8e0..3a0be2d4b2a 100644 --- a/src/include/catalog/pg_proc.dat +++ b/src/include/catalog/pg_proc.dat @@ -3986,9 +3986,6 @@ { oid => '1662', descr => 'trigger description', proname => 'pg_get_triggerdef', provolatile => 's', prorettype => 'text', proargtypes => 'oid', prosrc => 'pg_get_triggerdef' }, -{ oid => '1716', descr => 'deparse an encoded expression', - proname => 'pg_get_expr', provolatile => 's', prorettype => 'text', - proargtypes => 'pg_node_tree oid', prosrc => 'pg_get_expr' }, { oid => '1665', descr => 'name of sequence for a serial column', proname => 'pg_get_serial_sequence', provolatile => 's', prorettype => 'text', proargtypes => 'text text', prosrc => 'pg_get_serial_sequence' }, @@ -8518,7 +8515,7 @@ { oid => '2509', descr => 'deparse an encoded expression with pretty-print option', proname => 'pg_get_expr', provolatile => 's', prorettype => 'text', - proargtypes => 'pg_node_tree oid bool', prosrc => 'pg_get_expr_ext' }, + proargtypes => 'pg_node_tree oid bool', prosrc => 'pg_get_expr' }, { oid => '2510', descr => 'get the prepared statements for this session', proname => 'pg_prepared_statement', prorows => '1000', proretset => 't', provolatile => 's', proparallel => 'r', prorettype => 'record', -- 2.43.0 --3/nz5wg6+DYwHsLU Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v2-0006-Handle-pg_get_triggerdef-default-args-in-system_f.patch" ^ permalink raw reply [nested|flat] 248+ messages in thread
* [PATCH v7 5/6] Handle pg_get_expr default args in system_functions.sql @ 2025-12-09 19:17 Mark Wong <[email protected]> 0 siblings, 0 replies; 248+ messages in thread From: Mark Wong @ 2025-12-09 19:17 UTC (permalink / raw) Modernize pg_get_expr to use proargdefaults to handle the optional pretty argument. That also means any direct function calls now needs to set the pretty parameter. --- src/backend/commands/tablecmds.c | 5 +++-- src/backend/utils/adt/ruleutils.c | 17 ----------------- src/include/catalog/pg_proc.dat | 9 ++++----- 3 files changed, 7 insertions(+), 24 deletions(-) diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index eec09ba1ded..73eb6322daf 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -17695,8 +17695,9 @@ decompile_conbin(HeapTuple contup, TupleDesc tupdesc) if (isnull) elog(ERROR, "null conbin for constraint %u", con->oid); - expr = DirectFunctionCall2(pg_get_expr, attr, - ObjectIdGetDatum(con->conrelid)); + expr = DirectFunctionCall3(pg_get_expr, attr, + ObjectIdGetDatum(con->conrelid), + BoolGetDatum(false)); return TextDatumGetCString(expr); } diff --git a/src/backend/utils/adt/ruleutils.c b/src/backend/utils/adt/ruleutils.c index 2d39bce7fd7..707f83d4310 100644 --- a/src/backend/utils/adt/ruleutils.c +++ b/src/backend/utils/adt/ruleutils.c @@ -2932,23 +2932,6 @@ decompile_column_index_array(Datum column_index_array, Oid relId, */ Datum pg_get_expr(PG_FUNCTION_ARGS) -{ - text *expr = PG_GETARG_TEXT_PP(0); - Oid relid = PG_GETARG_OID(1); - text *result; - int prettyFlags; - - prettyFlags = PRETTYFLAG_INDENT; - - result = pg_get_expr_worker(expr, relid, prettyFlags); - if (result) - PG_RETURN_TEXT_P(result); - else - PG_RETURN_NULL(); -} - -Datum -pg_get_expr_ext(PG_FUNCTION_ARGS) { text *expr = PG_GETARG_TEXT_PP(0); Oid relid = PG_GETARG_OID(1); diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat index 39139fd9e3b..855529509de 100644 --- a/src/include/catalog/pg_proc.dat +++ b/src/include/catalog/pg_proc.dat @@ -4006,9 +4006,6 @@ { oid => '1662', descr => 'trigger description', proname => 'pg_get_triggerdef', provolatile => 's', prorettype => 'text', proargtypes => 'oid', prosrc => 'pg_get_triggerdef' }, -{ oid => '1716', descr => 'deparse an encoded expression', - proname => 'pg_get_expr', provolatile => 's', prorettype => 'text', - proargtypes => 'pg_node_tree oid', prosrc => 'pg_get_expr' }, { oid => '1665', descr => 'name of sequence for a serial column', proname => 'pg_get_serial_sequence', provolatile => 's', prorettype => 'text', proargtypes => 'text text', prosrc => 'pg_get_serial_sequence' }, @@ -8638,9 +8635,11 @@ pronargdefaults => '1', proargdefaults => '{NULL}', prosrc => 'pg_get_database_ddl' }, { oid => '2509', - descr => 'deparse an encoded expression with pretty-print option', + descr => 'deparse an encoded expression', proname => 'pg_get_expr', provolatile => 's', prorettype => 'text', - proargtypes => 'pg_node_tree oid bool', prosrc => 'pg_get_expr_ext' }, + proargtypes => 'pg_node_tree oid bool', + proargnames => '{expr,relation,pretty}', proargdefaults => '{false}', + prosrc => 'pg_get_expr' }, { oid => '2510', descr => 'get the prepared statements for this session', proname => 'pg_prepared_statement', prorows => '1000', proretset => 't', provolatile => 's', proparallel => 'r', prorettype => 'record', -- 2.52.0 --GzYugJnip6WHHvTk Content-Type: text/plain; charset=us-ascii Content-Disposition: attachment; filename=v7-0006-Handle-pg_get_triggerdef-default-args-in-system_f.patch ^ permalink raw reply [nested|flat] 248+ messages in thread
* [PATCH v5 5/6] Handle pg_get_expr default args in system_functions.sql @ 2025-12-09 19:17 Mark Wong <[email protected]> 0 siblings, 0 replies; 248+ messages in thread From: Mark Wong @ 2025-12-09 19:17 UTC (permalink / raw) Modernize pg_get_expr to use proargdefaults to handle the optional pretty argument. That also means any direct function calls now needs to set the pretty parameter. --- src/backend/commands/tablecmds.c | 5 +++-- src/backend/utils/adt/ruleutils.c | 17 ----------------- src/include/catalog/pg_proc.dat | 7 +++---- 3 files changed, 6 insertions(+), 23 deletions(-) diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 0ce2e81f9c2..fad4202b1ff 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -17694,8 +17694,9 @@ decompile_conbin(HeapTuple contup, TupleDesc tupdesc) if (isnull) elog(ERROR, "null conbin for constraint %u", con->oid); - expr = DirectFunctionCall2(pg_get_expr, attr, - ObjectIdGetDatum(con->conrelid)); + expr = DirectFunctionCall3(pg_get_expr, attr, + ObjectIdGetDatum(con->conrelid), + BoolGetDatum(false)); return TextDatumGetCString(expr); } diff --git a/src/backend/utils/adt/ruleutils.c b/src/backend/utils/adt/ruleutils.c index 1afa2531f30..972f89eafbc 100644 --- a/src/backend/utils/adt/ruleutils.c +++ b/src/backend/utils/adt/ruleutils.c @@ -2932,23 +2932,6 @@ decompile_column_index_array(Datum column_index_array, Oid relId, */ Datum pg_get_expr(PG_FUNCTION_ARGS) -{ - text *expr = PG_GETARG_TEXT_PP(0); - Oid relid = PG_GETARG_OID(1); - text *result; - int prettyFlags; - - prettyFlags = PRETTYFLAG_INDENT; - - result = pg_get_expr_worker(expr, relid, prettyFlags); - if (result) - PG_RETURN_TEXT_P(result); - else - PG_RETURN_NULL(); -} - -Datum -pg_get_expr_ext(PG_FUNCTION_ARGS) { text *expr = PG_GETARG_TEXT_PP(0); Oid relid = PG_GETARG_OID(1); diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat index e148b1ad8e3..f36f4625e50 100644 --- a/src/include/catalog/pg_proc.dat +++ b/src/include/catalog/pg_proc.dat @@ -4000,9 +4000,6 @@ { oid => '1662', descr => 'trigger description', proname => 'pg_get_triggerdef', provolatile => 's', prorettype => 'text', proargtypes => 'oid', prosrc => 'pg_get_triggerdef' }, -{ oid => '1716', descr => 'deparse an encoded expression', - proname => 'pg_get_expr', provolatile => 's', prorettype => 'text', - proargtypes => 'pg_node_tree oid', prosrc => 'pg_get_expr' }, { oid => '1665', descr => 'name of sequence for a serial column', proname => 'pg_get_serial_sequence', provolatile => 's', prorettype => 'text', proargtypes => 'text text', prosrc => 'pg_get_serial_sequence' }, @@ -8595,7 +8592,9 @@ { oid => '2509', descr => 'deparse an encoded expression with pretty-print option', proname => 'pg_get_expr', provolatile => 's', prorettype => 'text', - proargtypes => 'pg_node_tree oid bool', prosrc => 'pg_get_expr_ext' }, + proargtypes => 'pg_node_tree oid bool', + proargnames => '{expr,relation,pretty}', proargdefaults => '{false}', + prosrc => 'pg_get_expr' }, { oid => '2510', descr => 'get the prepared statements for this session', proname => 'pg_prepared_statement', prorows => '1000', proretset => 't', provolatile => 's', proparallel => 'r', prorettype => 'record', -- 2.52.0 --m23X5uHFNxthGTU3 Content-Type: text/plain; charset=us-ascii Content-Disposition: attachment; filename=v5-0006-Handle-pg_get_triggerdef-default-args-in-system_f.patch ^ permalink raw reply [nested|flat] 248+ messages in thread
* [PATCH v8 5/6] Handle pg_get_expr default args in system_functions.sql @ 2025-12-09 19:17 Mark Wong <[email protected]> 0 siblings, 0 replies; 248+ messages in thread From: Mark Wong @ 2025-12-09 19:17 UTC (permalink / raw) Modernize pg_get_expr to use proargdefaults to handle the optional pretty argument. That also means any direct function calls now needs to set the pretty parameter. --- src/backend/commands/tablecmds.c | 5 +++-- src/backend/utils/adt/ruleutils.c | 17 ----------------- src/include/catalog/pg_proc.dat | 9 ++++----- 3 files changed, 7 insertions(+), 24 deletions(-) diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index a1845240a98..f063f744f6d 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -17730,8 +17730,9 @@ decompile_conbin(HeapTuple contup, TupleDesc tupdesc) if (isnull) elog(ERROR, "null conbin for constraint %u", con->oid); - expr = DirectFunctionCall2(pg_get_expr, attr, - ObjectIdGetDatum(con->conrelid)); + expr = DirectFunctionCall3(pg_get_expr, attr, + ObjectIdGetDatum(con->conrelid), + BoolGetDatum(false)); return TextDatumGetCString(expr); } diff --git a/src/backend/utils/adt/ruleutils.c b/src/backend/utils/adt/ruleutils.c index d83be8cf77d..e60478677e0 100644 --- a/src/backend/utils/adt/ruleutils.c +++ b/src/backend/utils/adt/ruleutils.c @@ -2932,23 +2932,6 @@ decompile_column_index_array(Datum column_index_array, Oid relId, */ Datum pg_get_expr(PG_FUNCTION_ARGS) -{ - text *expr = PG_GETARG_TEXT_PP(0); - Oid relid = PG_GETARG_OID(1); - text *result; - int prettyFlags; - - prettyFlags = PRETTYFLAG_INDENT; - - result = pg_get_expr_worker(expr, relid, prettyFlags); - if (result) - PG_RETURN_TEXT_P(result); - else - PG_RETURN_NULL(); -} - -Datum -pg_get_expr_ext(PG_FUNCTION_ARGS) { text *expr = PG_GETARG_TEXT_PP(0); Oid relid = PG_GETARG_OID(1); diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat index 7e452aa8c27..71bd2aaf3d9 100644 --- a/src/include/catalog/pg_proc.dat +++ b/src/include/catalog/pg_proc.dat @@ -4006,9 +4006,6 @@ { oid => '1662', descr => 'trigger description', proname => 'pg_get_triggerdef', provolatile => 's', prorettype => 'text', proargtypes => 'oid', prosrc => 'pg_get_triggerdef' }, -{ oid => '1716', descr => 'deparse an encoded expression', - proname => 'pg_get_expr', provolatile => 's', prorettype => 'text', - proargtypes => 'pg_node_tree oid', prosrc => 'pg_get_expr' }, { oid => '1665', descr => 'name of sequence for a serial column', proname => 'pg_get_serial_sequence', provolatile => 's', prorettype => 'text', proargtypes => 'text text', prosrc => 'pg_get_serial_sequence' }, @@ -8605,9 +8602,11 @@ proargmodes => '{i,v}', proargdefaults => '{NULL}', prosrc => 'pg_get_database_ddl' }, { oid => '2509', - descr => 'deparse an encoded expression with pretty-print option', + descr => 'deparse an encoded expression', proname => 'pg_get_expr', provolatile => 's', prorettype => 'text', - proargtypes => 'pg_node_tree oid bool', prosrc => 'pg_get_expr_ext' }, + proargtypes => 'pg_node_tree oid bool', + proargnames => '{expr,relation,pretty}', proargdefaults => '{false}', + prosrc => 'pg_get_expr' }, { oid => '2510', descr => 'get the prepared statements for this session', proname => 'pg_prepared_statement', prorows => '1000', proretset => 't', provolatile => 's', proparallel => 'r', prorettype => 'record', -- 2.53.0 --iWwo79nqhOvOs5kf Content-Type: text/plain; charset=us-ascii Content-Disposition: attachment; filename=v8-0006-Handle-pg_get_triggerdef-default-args-in-system_f.patch ^ permalink raw reply [nested|flat] 248+ messages in thread
* [PATCH v2 5/6] Handle pg_get_expr default args in system_functions.sql @ 2025-12-09 19:17 Mark Wong <[email protected]> 0 siblings, 0 replies; 248+ messages in thread From: Mark Wong @ 2025-12-09 19:17 UTC (permalink / raw) Modernize pg_get_expr to use CREATE OR REPLACE FUNCTION to handle the optional pretty argument. --- src/backend/catalog/system_functions.sql | 7 +++++++ src/backend/commands/tablecmds.c | 4 ++-- src/backend/utils/adt/ruleutils.c | 17 ----------------- src/include/catalog/pg_proc.dat | 5 +---- 4 files changed, 10 insertions(+), 23 deletions(-) diff --git a/src/backend/catalog/system_functions.sql b/src/backend/catalog/system_functions.sql index 1824faab231..a6f7cdf3a36 100644 --- a/src/backend/catalog/system_functions.sql +++ b/src/backend/catalog/system_functions.sql @@ -692,6 +692,13 @@ LANGUAGE INTERNAL PARALLEL SAFE AS 'pg_get_constraintdef'; +CREATE OR REPLACE FUNCTION + pg_get_expr(expr pg_node_tree, relation oid, pretty bool DEFAULT false) +RETURNS TEXT +LANGUAGE INTERNAL +PARALLEL SAFE +AS 'pg_get_expr'; + -- -- The default permissions for functions mean that anyone can execute them. -- A number of functions shouldn't be executable by just anyone, but rather diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..12c4ce08437 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -17480,8 +17480,8 @@ decompile_conbin(HeapTuple contup, TupleDesc tupdesc) if (isnull) elog(ERROR, "null conbin for constraint %u", con->oid); - expr = DirectFunctionCall2(pg_get_expr, attr, - ObjectIdGetDatum(con->conrelid)); + expr = DirectFunctionCall3(pg_get_expr, attr, + ObjectIdGetDatum(con->conrelid), false); return TextDatumGetCString(expr); } diff --git a/src/backend/utils/adt/ruleutils.c b/src/backend/utils/adt/ruleutils.c index 9faf340f0c6..305e3e80c41 100644 --- a/src/backend/utils/adt/ruleutils.c +++ b/src/backend/utils/adt/ruleutils.c @@ -2573,23 +2573,6 @@ decompile_column_index_array(Datum column_index_array, Oid relId, */ Datum pg_get_expr(PG_FUNCTION_ARGS) -{ - text *expr = PG_GETARG_TEXT_PP(0); - Oid relid = PG_GETARG_OID(1); - text *result; - int prettyFlags; - - prettyFlags = PRETTYFLAG_INDENT; - - result = pg_get_expr_worker(expr, relid, prettyFlags); - if (result) - PG_RETURN_TEXT_P(result); - else - PG_RETURN_NULL(); -} - -Datum -pg_get_expr_ext(PG_FUNCTION_ARGS) { text *expr = PG_GETARG_TEXT_PP(0); Oid relid = PG_GETARG_OID(1); diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat index 96eb7baf8e0..3a0be2d4b2a 100644 --- a/src/include/catalog/pg_proc.dat +++ b/src/include/catalog/pg_proc.dat @@ -3986,9 +3986,6 @@ { oid => '1662', descr => 'trigger description', proname => 'pg_get_triggerdef', provolatile => 's', prorettype => 'text', proargtypes => 'oid', prosrc => 'pg_get_triggerdef' }, -{ oid => '1716', descr => 'deparse an encoded expression', - proname => 'pg_get_expr', provolatile => 's', prorettype => 'text', - proargtypes => 'pg_node_tree oid', prosrc => 'pg_get_expr' }, { oid => '1665', descr => 'name of sequence for a serial column', proname => 'pg_get_serial_sequence', provolatile => 's', prorettype => 'text', proargtypes => 'text text', prosrc => 'pg_get_serial_sequence' }, @@ -8518,7 +8515,7 @@ { oid => '2509', descr => 'deparse an encoded expression with pretty-print option', proname => 'pg_get_expr', provolatile => 's', prorettype => 'text', - proargtypes => 'pg_node_tree oid bool', prosrc => 'pg_get_expr_ext' }, + proargtypes => 'pg_node_tree oid bool', prosrc => 'pg_get_expr' }, { oid => '2510', descr => 'get the prepared statements for this session', proname => 'pg_prepared_statement', prorows => '1000', proretset => 't', provolatile => 's', proparallel => 'r', prorettype => 'record', -- 2.43.0 --3/nz5wg6+DYwHsLU Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v2-0006-Handle-pg_get_triggerdef-default-args-in-system_f.patch" ^ permalink raw reply [nested|flat] 248+ messages in thread
* [PATCH v4 5/6] Handle pg_get_expr default args in system_functions.sql @ 2025-12-09 19:17 Mark Wong <[email protected]> 0 siblings, 0 replies; 248+ messages in thread From: Mark Wong @ 2025-12-09 19:17 UTC (permalink / raw) Modernize pg_get_expr to use proargdefaults to handle the optional pretty argument. That also means any direct function calls now needs to set the pretty parameter. --- src/backend/commands/tablecmds.c | 5 +++-- src/backend/utils/adt/ruleutils.c | 17 ----------------- src/include/catalog/pg_proc.dat | 7 +++---- 3 files changed, 6 insertions(+), 23 deletions(-) diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index b04b0dbd2a0..a523a512949 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -17477,8 +17477,9 @@ decompile_conbin(HeapTuple contup, TupleDesc tupdesc) if (isnull) elog(ERROR, "null conbin for constraint %u", con->oid); - expr = DirectFunctionCall2(pg_get_expr, attr, - ObjectIdGetDatum(con->conrelid)); + expr = DirectFunctionCall3(pg_get_expr, attr, + ObjectIdGetDatum(con->conrelid), + BoolGetDatum(false)); return TextDatumGetCString(expr); } diff --git a/src/backend/utils/adt/ruleutils.c b/src/backend/utils/adt/ruleutils.c index 03550f0d80b..a70807e84ca 100644 --- a/src/backend/utils/adt/ruleutils.c +++ b/src/backend/utils/adt/ruleutils.c @@ -2574,23 +2574,6 @@ decompile_column_index_array(Datum column_index_array, Oid relId, */ Datum pg_get_expr(PG_FUNCTION_ARGS) -{ - text *expr = PG_GETARG_TEXT_PP(0); - Oid relid = PG_GETARG_OID(1); - text *result; - int prettyFlags; - - prettyFlags = PRETTYFLAG_INDENT; - - result = pg_get_expr_worker(expr, relid, prettyFlags); - if (result) - PG_RETURN_TEXT_P(result); - else - PG_RETURN_NULL(); -} - -Datum -pg_get_expr_ext(PG_FUNCTION_ARGS) { text *expr = PG_GETARG_TEXT_PP(0); Oid relid = PG_GETARG_OID(1); diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat index 1d1b24a8f4c..69c1e5bb264 100644 --- a/src/include/catalog/pg_proc.dat +++ b/src/include/catalog/pg_proc.dat @@ -3987,9 +3987,6 @@ { oid => '1662', descr => 'trigger description', proname => 'pg_get_triggerdef', provolatile => 's', prorettype => 'text', proargtypes => 'oid', prosrc => 'pg_get_triggerdef' }, -{ oid => '1716', descr => 'deparse an encoded expression', - proname => 'pg_get_expr', provolatile => 's', prorettype => 'text', - proargtypes => 'pg_node_tree oid', prosrc => 'pg_get_expr' }, { oid => '1665', descr => 'name of sequence for a serial column', proname => 'pg_get_serial_sequence', provolatile => 's', prorettype => 'text', proargtypes => 'text text', prosrc => 'pg_get_serial_sequence' }, @@ -8531,7 +8528,9 @@ { oid => '2509', descr => 'deparse an encoded expression with pretty-print option', proname => 'pg_get_expr', provolatile => 's', prorettype => 'text', - proargtypes => 'pg_node_tree oid bool', prosrc => 'pg_get_expr_ext' }, + proargtypes => 'pg_node_tree oid bool', + proargnames => '{expr,relation,pretty}', proargdefaults => '{false}', + prosrc => 'pg_get_expr' }, { oid => '2510', descr => 'get the prepared statements for this session', proname => 'pg_prepared_statement', prorows => '1000', proretset => 't', provolatile => 's', proparallel => 'r', prorettype => 'record', -- 2.43.0 --eEEy3EHc57lA8spa Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v4-0006-Handle-pg_get_triggerdef-default-args-in-system_f.patch" ^ permalink raw reply [nested|flat] 248+ messages in thread
* [PATCH v8 5/6] Handle pg_get_expr default args in system_functions.sql @ 2025-12-09 19:17 Mark Wong <[email protected]> 0 siblings, 0 replies; 248+ messages in thread From: Mark Wong @ 2025-12-09 19:17 UTC (permalink / raw) Modernize pg_get_expr to use proargdefaults to handle the optional pretty argument. That also means any direct function calls now needs to set the pretty parameter. --- src/backend/commands/tablecmds.c | 5 +++-- src/backend/utils/adt/ruleutils.c | 17 ----------------- src/include/catalog/pg_proc.dat | 9 ++++----- 3 files changed, 7 insertions(+), 24 deletions(-) diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index a1845240a98..f063f744f6d 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -17730,8 +17730,9 @@ decompile_conbin(HeapTuple contup, TupleDesc tupdesc) if (isnull) elog(ERROR, "null conbin for constraint %u", con->oid); - expr = DirectFunctionCall2(pg_get_expr, attr, - ObjectIdGetDatum(con->conrelid)); + expr = DirectFunctionCall3(pg_get_expr, attr, + ObjectIdGetDatum(con->conrelid), + BoolGetDatum(false)); return TextDatumGetCString(expr); } diff --git a/src/backend/utils/adt/ruleutils.c b/src/backend/utils/adt/ruleutils.c index d83be8cf77d..e60478677e0 100644 --- a/src/backend/utils/adt/ruleutils.c +++ b/src/backend/utils/adt/ruleutils.c @@ -2932,23 +2932,6 @@ decompile_column_index_array(Datum column_index_array, Oid relId, */ Datum pg_get_expr(PG_FUNCTION_ARGS) -{ - text *expr = PG_GETARG_TEXT_PP(0); - Oid relid = PG_GETARG_OID(1); - text *result; - int prettyFlags; - - prettyFlags = PRETTYFLAG_INDENT; - - result = pg_get_expr_worker(expr, relid, prettyFlags); - if (result) - PG_RETURN_TEXT_P(result); - else - PG_RETURN_NULL(); -} - -Datum -pg_get_expr_ext(PG_FUNCTION_ARGS) { text *expr = PG_GETARG_TEXT_PP(0); Oid relid = PG_GETARG_OID(1); diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat index 7e452aa8c27..71bd2aaf3d9 100644 --- a/src/include/catalog/pg_proc.dat +++ b/src/include/catalog/pg_proc.dat @@ -4006,9 +4006,6 @@ { oid => '1662', descr => 'trigger description', proname => 'pg_get_triggerdef', provolatile => 's', prorettype => 'text', proargtypes => 'oid', prosrc => 'pg_get_triggerdef' }, -{ oid => '1716', descr => 'deparse an encoded expression', - proname => 'pg_get_expr', provolatile => 's', prorettype => 'text', - proargtypes => 'pg_node_tree oid', prosrc => 'pg_get_expr' }, { oid => '1665', descr => 'name of sequence for a serial column', proname => 'pg_get_serial_sequence', provolatile => 's', prorettype => 'text', proargtypes => 'text text', prosrc => 'pg_get_serial_sequence' }, @@ -8605,9 +8602,11 @@ proargmodes => '{i,v}', proargdefaults => '{NULL}', prosrc => 'pg_get_database_ddl' }, { oid => '2509', - descr => 'deparse an encoded expression with pretty-print option', + descr => 'deparse an encoded expression', proname => 'pg_get_expr', provolatile => 's', prorettype => 'text', - proargtypes => 'pg_node_tree oid bool', prosrc => 'pg_get_expr_ext' }, + proargtypes => 'pg_node_tree oid bool', + proargnames => '{expr,relation,pretty}', proargdefaults => '{false}', + prosrc => 'pg_get_expr' }, { oid => '2510', descr => 'get the prepared statements for this session', proname => 'pg_prepared_statement', prorows => '1000', proretset => 't', provolatile => 's', proparallel => 'r', prorettype => 'record', -- 2.53.0 --iWwo79nqhOvOs5kf Content-Type: text/plain; charset=us-ascii Content-Disposition: attachment; filename=v8-0006-Handle-pg_get_triggerdef-default-args-in-system_f.patch ^ permalink raw reply [nested|flat] 248+ messages in thread
* [PATCH v3 6/7] Handle pg_get_expr default args in system_functions.sql @ 2025-12-09 19:17 Mark Wong <[email protected]> 0 siblings, 0 replies; 248+ messages in thread From: Mark Wong @ 2025-12-09 19:17 UTC (permalink / raw) Modernize pg_get_expr to use CREATE OR REPLACE FUNCTION to handle the optional pretty argument. --- src/backend/catalog/system_functions.sql | 7 +++++++ src/backend/commands/tablecmds.c | 4 ++-- src/backend/utils/adt/ruleutils.c | 17 ----------------- src/include/catalog/pg_proc.dat | 5 +---- src/include/catalog/pg_retired.dat | 3 ++- 5 files changed, 12 insertions(+), 24 deletions(-) diff --git a/src/backend/catalog/system_functions.sql b/src/backend/catalog/system_functions.sql index 1824faab231..a6f7cdf3a36 100644 --- a/src/backend/catalog/system_functions.sql +++ b/src/backend/catalog/system_functions.sql @@ -692,6 +692,13 @@ LANGUAGE INTERNAL PARALLEL SAFE AS 'pg_get_constraintdef'; +CREATE OR REPLACE FUNCTION + pg_get_expr(expr pg_node_tree, relation oid, pretty bool DEFAULT false) +RETURNS TEXT +LANGUAGE INTERNAL +PARALLEL SAFE +AS 'pg_get_expr'; + -- -- The default permissions for functions mean that anyone can execute them. -- A number of functions shouldn't be executable by just anyone, but rather diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..12c4ce08437 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -17480,8 +17480,8 @@ decompile_conbin(HeapTuple contup, TupleDesc tupdesc) if (isnull) elog(ERROR, "null conbin for constraint %u", con->oid); - expr = DirectFunctionCall2(pg_get_expr, attr, - ObjectIdGetDatum(con->conrelid)); + expr = DirectFunctionCall3(pg_get_expr, attr, + ObjectIdGetDatum(con->conrelid), false); return TextDatumGetCString(expr); } diff --git a/src/backend/utils/adt/ruleutils.c b/src/backend/utils/adt/ruleutils.c index 4f2c93f1ee2..d87b361a093 100644 --- a/src/backend/utils/adt/ruleutils.c +++ b/src/backend/utils/adt/ruleutils.c @@ -2573,23 +2573,6 @@ decompile_column_index_array(Datum column_index_array, Oid relId, */ Datum pg_get_expr(PG_FUNCTION_ARGS) -{ - text *expr = PG_GETARG_TEXT_PP(0); - Oid relid = PG_GETARG_OID(1); - text *result; - int prettyFlags; - - prettyFlags = PRETTYFLAG_INDENT; - - result = pg_get_expr_worker(expr, relid, prettyFlags); - if (result) - PG_RETURN_TEXT_P(result); - else - PG_RETURN_NULL(); -} - -Datum -pg_get_expr_ext(PG_FUNCTION_ARGS) { text *expr = PG_GETARG_TEXT_PP(0); Oid relid = PG_GETARG_OID(1); diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat index ffec11c5539..4304ab220ba 100644 --- a/src/include/catalog/pg_proc.dat +++ b/src/include/catalog/pg_proc.dat @@ -3986,9 +3986,6 @@ { oid => '1662', descr => 'trigger description', proname => 'pg_get_triggerdef', provolatile => 's', prorettype => 'text', proargtypes => 'oid', prosrc => 'pg_get_triggerdef' }, -{ oid => '1716', descr => 'deparse an encoded expression', - proname => 'pg_get_expr', provolatile => 's', prorettype => 'text', - proargtypes => 'pg_node_tree oid', prosrc => 'pg_get_expr' }, { oid => '1665', descr => 'name of sequence for a serial column', proname => 'pg_get_serial_sequence', provolatile => 's', prorettype => 'text', proargtypes => 'text text', prosrc => 'pg_get_serial_sequence' }, @@ -8518,7 +8515,7 @@ { oid => '2509', descr => 'deparse an encoded expression with pretty-print option', proname => 'pg_get_expr', provolatile => 's', prorettype => 'text', - proargtypes => 'pg_node_tree oid bool', prosrc => 'pg_get_expr_ext' }, + proargtypes => 'pg_node_tree oid bool', prosrc => 'pg_get_expr' }, { oid => '2510', descr => 'get the prepared statements for this session', proname => 'pg_prepared_statement', prorows => '1000', proretset => 't', provolatile => 's', proparallel => 'r', prorettype => 'record', diff --git a/src/include/catalog/pg_retired.dat b/src/include/catalog/pg_retired.dat index 90928a9cb00..8b5f58850f6 100644 --- a/src/include/catalog/pg_retired.dat +++ b/src/include/catalog/pg_retired.dat @@ -21,6 +21,7 @@ { oid => '1573', proname => 'pg_get_ruledef' }, { oid => '1640', proname => 'pg_get_viewdef' }, { oid => '1641', proname => 'pg_get_viewdef' }, -{ oid => '1643', proname => 'pg_get_indexdef' } +{ oid => '1643', proname => 'pg_get_indexdef' }, +{ oid => '1716', proname => 'pg_get_expr' } ] -- 2.43.0 --zd8Z8rlPOcTi77n/ Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v3-0007-Handle-pg_get_triggerdef-default-args-in-system_f.patch" ^ permalink raw reply [nested|flat] 248+ messages in thread
* [PATCH v4 5/6] Handle pg_get_expr default args in system_functions.sql @ 2025-12-09 19:17 Mark Wong <[email protected]> 0 siblings, 0 replies; 248+ messages in thread From: Mark Wong @ 2025-12-09 19:17 UTC (permalink / raw) Modernize pg_get_expr to use proargdefaults to handle the optional pretty argument. That also means any direct function calls now needs to set the pretty parameter. --- src/backend/commands/tablecmds.c | 5 +++-- src/backend/utils/adt/ruleutils.c | 17 ----------------- src/include/catalog/pg_proc.dat | 7 +++---- 3 files changed, 6 insertions(+), 23 deletions(-) diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index b04b0dbd2a0..a523a512949 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -17477,8 +17477,9 @@ decompile_conbin(HeapTuple contup, TupleDesc tupdesc) if (isnull) elog(ERROR, "null conbin for constraint %u", con->oid); - expr = DirectFunctionCall2(pg_get_expr, attr, - ObjectIdGetDatum(con->conrelid)); + expr = DirectFunctionCall3(pg_get_expr, attr, + ObjectIdGetDatum(con->conrelid), + BoolGetDatum(false)); return TextDatumGetCString(expr); } diff --git a/src/backend/utils/adt/ruleutils.c b/src/backend/utils/adt/ruleutils.c index 03550f0d80b..a70807e84ca 100644 --- a/src/backend/utils/adt/ruleutils.c +++ b/src/backend/utils/adt/ruleutils.c @@ -2574,23 +2574,6 @@ decompile_column_index_array(Datum column_index_array, Oid relId, */ Datum pg_get_expr(PG_FUNCTION_ARGS) -{ - text *expr = PG_GETARG_TEXT_PP(0); - Oid relid = PG_GETARG_OID(1); - text *result; - int prettyFlags; - - prettyFlags = PRETTYFLAG_INDENT; - - result = pg_get_expr_worker(expr, relid, prettyFlags); - if (result) - PG_RETURN_TEXT_P(result); - else - PG_RETURN_NULL(); -} - -Datum -pg_get_expr_ext(PG_FUNCTION_ARGS) { text *expr = PG_GETARG_TEXT_PP(0); Oid relid = PG_GETARG_OID(1); diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat index 1d1b24a8f4c..69c1e5bb264 100644 --- a/src/include/catalog/pg_proc.dat +++ b/src/include/catalog/pg_proc.dat @@ -3987,9 +3987,6 @@ { oid => '1662', descr => 'trigger description', proname => 'pg_get_triggerdef', provolatile => 's', prorettype => 'text', proargtypes => 'oid', prosrc => 'pg_get_triggerdef' }, -{ oid => '1716', descr => 'deparse an encoded expression', - proname => 'pg_get_expr', provolatile => 's', prorettype => 'text', - proargtypes => 'pg_node_tree oid', prosrc => 'pg_get_expr' }, { oid => '1665', descr => 'name of sequence for a serial column', proname => 'pg_get_serial_sequence', provolatile => 's', prorettype => 'text', proargtypes => 'text text', prosrc => 'pg_get_serial_sequence' }, @@ -8531,7 +8528,9 @@ { oid => '2509', descr => 'deparse an encoded expression with pretty-print option', proname => 'pg_get_expr', provolatile => 's', prorettype => 'text', - proargtypes => 'pg_node_tree oid bool', prosrc => 'pg_get_expr_ext' }, + proargtypes => 'pg_node_tree oid bool', + proargnames => '{expr,relation,pretty}', proargdefaults => '{false}', + prosrc => 'pg_get_expr' }, { oid => '2510', descr => 'get the prepared statements for this session', proname => 'pg_prepared_statement', prorows => '1000', proretset => 't', provolatile => 's', proparallel => 'r', prorettype => 'record', -- 2.43.0 --eEEy3EHc57lA8spa Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v4-0006-Handle-pg_get_triggerdef-default-args-in-system_f.patch" ^ permalink raw reply [nested|flat] 248+ messages in thread
* [PATCH v7 5/6] Handle pg_get_expr default args in system_functions.sql @ 2025-12-09 19:17 Mark Wong <[email protected]> 0 siblings, 0 replies; 248+ messages in thread From: Mark Wong @ 2025-12-09 19:17 UTC (permalink / raw) Modernize pg_get_expr to use proargdefaults to handle the optional pretty argument. That also means any direct function calls now needs to set the pretty parameter. --- src/backend/commands/tablecmds.c | 5 +++-- src/backend/utils/adt/ruleutils.c | 17 ----------------- src/include/catalog/pg_proc.dat | 9 ++++----- 3 files changed, 7 insertions(+), 24 deletions(-) diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index eec09ba1ded..73eb6322daf 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -17695,8 +17695,9 @@ decompile_conbin(HeapTuple contup, TupleDesc tupdesc) if (isnull) elog(ERROR, "null conbin for constraint %u", con->oid); - expr = DirectFunctionCall2(pg_get_expr, attr, - ObjectIdGetDatum(con->conrelid)); + expr = DirectFunctionCall3(pg_get_expr, attr, + ObjectIdGetDatum(con->conrelid), + BoolGetDatum(false)); return TextDatumGetCString(expr); } diff --git a/src/backend/utils/adt/ruleutils.c b/src/backend/utils/adt/ruleutils.c index 2d39bce7fd7..707f83d4310 100644 --- a/src/backend/utils/adt/ruleutils.c +++ b/src/backend/utils/adt/ruleutils.c @@ -2932,23 +2932,6 @@ decompile_column_index_array(Datum column_index_array, Oid relId, */ Datum pg_get_expr(PG_FUNCTION_ARGS) -{ - text *expr = PG_GETARG_TEXT_PP(0); - Oid relid = PG_GETARG_OID(1); - text *result; - int prettyFlags; - - prettyFlags = PRETTYFLAG_INDENT; - - result = pg_get_expr_worker(expr, relid, prettyFlags); - if (result) - PG_RETURN_TEXT_P(result); - else - PG_RETURN_NULL(); -} - -Datum -pg_get_expr_ext(PG_FUNCTION_ARGS) { text *expr = PG_GETARG_TEXT_PP(0); Oid relid = PG_GETARG_OID(1); diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat index 39139fd9e3b..855529509de 100644 --- a/src/include/catalog/pg_proc.dat +++ b/src/include/catalog/pg_proc.dat @@ -4006,9 +4006,6 @@ { oid => '1662', descr => 'trigger description', proname => 'pg_get_triggerdef', provolatile => 's', prorettype => 'text', proargtypes => 'oid', prosrc => 'pg_get_triggerdef' }, -{ oid => '1716', descr => 'deparse an encoded expression', - proname => 'pg_get_expr', provolatile => 's', prorettype => 'text', - proargtypes => 'pg_node_tree oid', prosrc => 'pg_get_expr' }, { oid => '1665', descr => 'name of sequence for a serial column', proname => 'pg_get_serial_sequence', provolatile => 's', prorettype => 'text', proargtypes => 'text text', prosrc => 'pg_get_serial_sequence' }, @@ -8638,9 +8635,11 @@ pronargdefaults => '1', proargdefaults => '{NULL}', prosrc => 'pg_get_database_ddl' }, { oid => '2509', - descr => 'deparse an encoded expression with pretty-print option', + descr => 'deparse an encoded expression', proname => 'pg_get_expr', provolatile => 's', prorettype => 'text', - proargtypes => 'pg_node_tree oid bool', prosrc => 'pg_get_expr_ext' }, + proargtypes => 'pg_node_tree oid bool', + proargnames => '{expr,relation,pretty}', proargdefaults => '{false}', + prosrc => 'pg_get_expr' }, { oid => '2510', descr => 'get the prepared statements for this session', proname => 'pg_prepared_statement', prorows => '1000', proretset => 't', provolatile => 's', proparallel => 'r', prorettype => 'record', -- 2.52.0 --GzYugJnip6WHHvTk Content-Type: text/plain; charset=us-ascii Content-Disposition: attachment; filename=v7-0006-Handle-pg_get_triggerdef-default-args-in-system_f.patch ^ permalink raw reply [nested|flat] 248+ messages in thread
* [PATCH v3 6/7] Handle pg_get_expr default args in system_functions.sql @ 2025-12-09 19:17 Mark Wong <[email protected]> 0 siblings, 0 replies; 248+ messages in thread From: Mark Wong @ 2025-12-09 19:17 UTC (permalink / raw) Modernize pg_get_expr to use CREATE OR REPLACE FUNCTION to handle the optional pretty argument. --- src/backend/catalog/system_functions.sql | 7 +++++++ src/backend/commands/tablecmds.c | 4 ++-- src/backend/utils/adt/ruleutils.c | 17 ----------------- src/include/catalog/pg_proc.dat | 5 +---- src/include/catalog/pg_retired.dat | 3 ++- 5 files changed, 12 insertions(+), 24 deletions(-) diff --git a/src/backend/catalog/system_functions.sql b/src/backend/catalog/system_functions.sql index 1824faab231..a6f7cdf3a36 100644 --- a/src/backend/catalog/system_functions.sql +++ b/src/backend/catalog/system_functions.sql @@ -692,6 +692,13 @@ LANGUAGE INTERNAL PARALLEL SAFE AS 'pg_get_constraintdef'; +CREATE OR REPLACE FUNCTION + pg_get_expr(expr pg_node_tree, relation oid, pretty bool DEFAULT false) +RETURNS TEXT +LANGUAGE INTERNAL +PARALLEL SAFE +AS 'pg_get_expr'; + -- -- The default permissions for functions mean that anyone can execute them. -- A number of functions shouldn't be executable by just anyone, but rather diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..12c4ce08437 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -17480,8 +17480,8 @@ decompile_conbin(HeapTuple contup, TupleDesc tupdesc) if (isnull) elog(ERROR, "null conbin for constraint %u", con->oid); - expr = DirectFunctionCall2(pg_get_expr, attr, - ObjectIdGetDatum(con->conrelid)); + expr = DirectFunctionCall3(pg_get_expr, attr, + ObjectIdGetDatum(con->conrelid), false); return TextDatumGetCString(expr); } diff --git a/src/backend/utils/adt/ruleutils.c b/src/backend/utils/adt/ruleutils.c index 4f2c93f1ee2..d87b361a093 100644 --- a/src/backend/utils/adt/ruleutils.c +++ b/src/backend/utils/adt/ruleutils.c @@ -2573,23 +2573,6 @@ decompile_column_index_array(Datum column_index_array, Oid relId, */ Datum pg_get_expr(PG_FUNCTION_ARGS) -{ - text *expr = PG_GETARG_TEXT_PP(0); - Oid relid = PG_GETARG_OID(1); - text *result; - int prettyFlags; - - prettyFlags = PRETTYFLAG_INDENT; - - result = pg_get_expr_worker(expr, relid, prettyFlags); - if (result) - PG_RETURN_TEXT_P(result); - else - PG_RETURN_NULL(); -} - -Datum -pg_get_expr_ext(PG_FUNCTION_ARGS) { text *expr = PG_GETARG_TEXT_PP(0); Oid relid = PG_GETARG_OID(1); diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat index ffec11c5539..4304ab220ba 100644 --- a/src/include/catalog/pg_proc.dat +++ b/src/include/catalog/pg_proc.dat @@ -3986,9 +3986,6 @@ { oid => '1662', descr => 'trigger description', proname => 'pg_get_triggerdef', provolatile => 's', prorettype => 'text', proargtypes => 'oid', prosrc => 'pg_get_triggerdef' }, -{ oid => '1716', descr => 'deparse an encoded expression', - proname => 'pg_get_expr', provolatile => 's', prorettype => 'text', - proargtypes => 'pg_node_tree oid', prosrc => 'pg_get_expr' }, { oid => '1665', descr => 'name of sequence for a serial column', proname => 'pg_get_serial_sequence', provolatile => 's', prorettype => 'text', proargtypes => 'text text', prosrc => 'pg_get_serial_sequence' }, @@ -8518,7 +8515,7 @@ { oid => '2509', descr => 'deparse an encoded expression with pretty-print option', proname => 'pg_get_expr', provolatile => 's', prorettype => 'text', - proargtypes => 'pg_node_tree oid bool', prosrc => 'pg_get_expr_ext' }, + proargtypes => 'pg_node_tree oid bool', prosrc => 'pg_get_expr' }, { oid => '2510', descr => 'get the prepared statements for this session', proname => 'pg_prepared_statement', prorows => '1000', proretset => 't', provolatile => 's', proparallel => 'r', prorettype => 'record', diff --git a/src/include/catalog/pg_retired.dat b/src/include/catalog/pg_retired.dat index 90928a9cb00..8b5f58850f6 100644 --- a/src/include/catalog/pg_retired.dat +++ b/src/include/catalog/pg_retired.dat @@ -21,6 +21,7 @@ { oid => '1573', proname => 'pg_get_ruledef' }, { oid => '1640', proname => 'pg_get_viewdef' }, { oid => '1641', proname => 'pg_get_viewdef' }, -{ oid => '1643', proname => 'pg_get_indexdef' } +{ oid => '1643', proname => 'pg_get_indexdef' }, +{ oid => '1716', proname => 'pg_get_expr' } ] -- 2.43.0 --zd8Z8rlPOcTi77n/ Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="v3-0007-Handle-pg_get_triggerdef-default-args-in-system_f.patch" ^ permalink raw reply [nested|flat] 248+ messages in thread
* [PATCH v8.1 5/6] Handle pg_get_expr default args in system_functions.sql @ 2025-12-09 19:17 Mark Wong <[email protected]> 0 siblings, 0 replies; 248+ messages in thread From: Mark Wong @ 2025-12-09 19:17 UTC (permalink / raw) Modernize pg_get_expr to use proargdefaults to handle the optional pretty argument. That also means any direct function calls now needs to set the pretty parameter. --- src/backend/commands/tablecmds.c | 5 +++-- src/backend/utils/adt/ruleutils.c | 17 ----------------- src/include/catalog/pg_proc.dat | 9 ++++----- 3 files changed, 7 insertions(+), 24 deletions(-) diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index a1845240a98..f063f744f6d 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -17730,8 +17730,9 @@ decompile_conbin(HeapTuple contup, TupleDesc tupdesc) if (isnull) elog(ERROR, "null conbin for constraint %u", con->oid); - expr = DirectFunctionCall2(pg_get_expr, attr, - ObjectIdGetDatum(con->conrelid)); + expr = DirectFunctionCall3(pg_get_expr, attr, + ObjectIdGetDatum(con->conrelid), + BoolGetDatum(false)); return TextDatumGetCString(expr); } diff --git a/src/backend/utils/adt/ruleutils.c b/src/backend/utils/adt/ruleutils.c index d83be8cf77d..e60478677e0 100644 --- a/src/backend/utils/adt/ruleutils.c +++ b/src/backend/utils/adt/ruleutils.c @@ -2932,23 +2932,6 @@ decompile_column_index_array(Datum column_index_array, Oid relId, */ Datum pg_get_expr(PG_FUNCTION_ARGS) -{ - text *expr = PG_GETARG_TEXT_PP(0); - Oid relid = PG_GETARG_OID(1); - text *result; - int prettyFlags; - - prettyFlags = PRETTYFLAG_INDENT; - - result = pg_get_expr_worker(expr, relid, prettyFlags); - if (result) - PG_RETURN_TEXT_P(result); - else - PG_RETURN_NULL(); -} - -Datum -pg_get_expr_ext(PG_FUNCTION_ARGS) { text *expr = PG_GETARG_TEXT_PP(0); Oid relid = PG_GETARG_OID(1); diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat index e610a6213ec..df43469be3d 100644 --- a/src/include/catalog/pg_proc.dat +++ b/src/include/catalog/pg_proc.dat @@ -4006,9 +4006,6 @@ { oid => '1662', descr => 'trigger description', proname => 'pg_get_triggerdef', provolatile => 's', prorettype => 'text', proargtypes => 'oid', prosrc => 'pg_get_triggerdef' }, -{ oid => '1716', descr => 'deparse an encoded expression', - proname => 'pg_get_expr', provolatile => 's', prorettype => 'text', - proargtypes => 'pg_node_tree oid', prosrc => 'pg_get_expr' }, { oid => '1665', descr => 'name of sequence for a serial column', proname => 'pg_get_serial_sequence', provolatile => 's', prorettype => 'text', proargtypes => 'text text', prosrc => 'pg_get_serial_sequence' }, @@ -8605,9 +8602,11 @@ proargmodes => '{i,v}', proargdefaults => '{NULL}', prosrc => 'pg_get_database_ddl' }, { oid => '2509', - descr => 'deparse an encoded expression with pretty-print option', + descr => 'deparse an encoded expression', proname => 'pg_get_expr', provolatile => 's', prorettype => 'text', - proargtypes => 'pg_node_tree oid bool', prosrc => 'pg_get_expr_ext' }, + proargtypes => 'pg_node_tree oid bool', + proargnames => '{expr,relation,pretty}', proargdefaults => '{false}', + prosrc => 'pg_get_expr' }, { oid => '2510', descr => 'get the prepared statements for this session', proname => 'pg_prepared_statement', prorows => '1000', proretset => 't', provolatile => 's', proparallel => 'r', prorettype => 'record', -- 2.53.0 --AcCatzXgbvyipyEy Content-Type: text/plain; charset=us-ascii Content-Disposition: attachment; filename=v8.1-0006-Handle-pg_get_triggerdef-default-args-in-system.patch ^ permalink raw reply [nested|flat] 248+ messages in thread
* [PATCH v1 5/6] Handle pg_get_expr default args in system_functions.sql @ 2025-12-09 19:17 Mark Wong <[email protected]> 0 siblings, 0 replies; 248+ messages in thread From: Mark Wong @ 2025-12-09 19:17 UTC (permalink / raw) Modernize pg_get_expr to use CREATE OR REPLACE FUNCTION to handle the optional pretty argument. --- src/backend/catalog/system_functions.sql | 7 +++++++ src/backend/utils/adt/ruleutils.c | 17 ----------------- src/include/catalog/pg_proc.dat | 5 +---- 3 files changed, 8 insertions(+), 21 deletions(-) diff --git a/src/backend/catalog/system_functions.sql b/src/backend/catalog/system_functions.sql index 1f89dcc7908..81d210a9c45 100644 --- a/src/backend/catalog/system_functions.sql +++ b/src/backend/catalog/system_functions.sql @@ -692,6 +692,13 @@ LANGUAGE INTERNAL PARALLEL SAFE AS 'pg_get_constraintdef'; +CREATE OR REPLACE FUNCTION + pg_get_expr(expr pg_node_tree, relation oid, pretty bool DEFAULT false) +RETURNS TEXT +LANGUAGE INTERNAL +PARALLEL SAFE +AS 'pg_get_expr'; + -- -- The default permissions for functions mean that anyone can execute them. -- A number of functions shouldn't be executable by just anyone, but rather diff --git a/src/backend/utils/adt/ruleutils.c b/src/backend/utils/adt/ruleutils.c index 416144c49f5..9effa02fa2e 100644 --- a/src/backend/utils/adt/ruleutils.c +++ b/src/backend/utils/adt/ruleutils.c @@ -2573,23 +2573,6 @@ decompile_column_index_array(Datum column_index_array, Oid relId, */ Datum pg_get_expr(PG_FUNCTION_ARGS) -{ - text *expr = PG_GETARG_TEXT_PP(0); - Oid relid = PG_GETARG_OID(1); - text *result; - int prettyFlags; - - prettyFlags = PRETTYFLAG_INDENT; - - result = pg_get_expr_worker(expr, relid, prettyFlags); - if (result) - PG_RETURN_TEXT_P(result); - else - PG_RETURN_NULL(); -} - -Datum -pg_get_expr_ext(PG_FUNCTION_ARGS) { text *expr = PG_GETARG_TEXT_PP(0); Oid relid = PG_GETARG_OID(1); diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat index a9431ea4037..10c5286bd7d 100644 --- a/src/include/catalog/pg_proc.dat +++ b/src/include/catalog/pg_proc.dat @@ -3977,9 +3977,6 @@ { oid => '1662', descr => 'trigger description', proname => 'pg_get_triggerdef', provolatile => 's', prorettype => 'text', proargtypes => 'oid', prosrc => 'pg_get_triggerdef' }, -{ oid => '1716', descr => 'deparse an encoded expression', - proname => 'pg_get_expr', provolatile => 's', prorettype => 'text', - proargtypes => 'pg_node_tree oid', prosrc => 'pg_get_expr' }, { oid => '1665', descr => 'name of sequence for a serial column', proname => 'pg_get_serial_sequence', provolatile => 's', prorettype => 'text', proargtypes => 'text text', prosrc => 'pg_get_serial_sequence' }, @@ -8502,7 +8499,7 @@ { oid => '2509', descr => 'deparse an encoded expression with pretty-print option', proname => 'pg_get_expr', provolatile => 's', prorettype => 'text', - proargtypes => 'pg_node_tree oid bool', prosrc => 'pg_get_expr_ext' }, + proargtypes => 'pg_node_tree oid bool', prosrc => 'pg_get_expr' }, { oid => '2510', descr => 'get the prepared statements for this session', proname => 'pg_prepared_statement', prorows => '1000', proretset => 't', provolatile => 's', proparallel => 'r', prorettype => 'record', -- 2.51.2 --IRGsBYp1UN8d6WrT Content-Type: text/plain; charset=us-ascii Content-Disposition: attachment; filename=v1-0006-Handle-pg_get_triggerdef-default-args-in-system_f.patch ^ permalink raw reply [nested|flat] 248+ messages in thread
* [PATCH v8.1 5/6] Handle pg_get_expr default args in system_functions.sql @ 2025-12-09 19:17 Mark Wong <[email protected]> 0 siblings, 0 replies; 248+ messages in thread From: Mark Wong @ 2025-12-09 19:17 UTC (permalink / raw) Modernize pg_get_expr to use proargdefaults to handle the optional pretty argument. That also means any direct function calls now needs to set the pretty parameter. --- src/backend/commands/tablecmds.c | 5 +++-- src/backend/utils/adt/ruleutils.c | 17 ----------------- src/include/catalog/pg_proc.dat | 9 ++++----- 3 files changed, 7 insertions(+), 24 deletions(-) diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index a1845240a98..f063f744f6d 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -17730,8 +17730,9 @@ decompile_conbin(HeapTuple contup, TupleDesc tupdesc) if (isnull) elog(ERROR, "null conbin for constraint %u", con->oid); - expr = DirectFunctionCall2(pg_get_expr, attr, - ObjectIdGetDatum(con->conrelid)); + expr = DirectFunctionCall3(pg_get_expr, attr, + ObjectIdGetDatum(con->conrelid), + BoolGetDatum(false)); return TextDatumGetCString(expr); } diff --git a/src/backend/utils/adt/ruleutils.c b/src/backend/utils/adt/ruleutils.c index d83be8cf77d..e60478677e0 100644 --- a/src/backend/utils/adt/ruleutils.c +++ b/src/backend/utils/adt/ruleutils.c @@ -2932,23 +2932,6 @@ decompile_column_index_array(Datum column_index_array, Oid relId, */ Datum pg_get_expr(PG_FUNCTION_ARGS) -{ - text *expr = PG_GETARG_TEXT_PP(0); - Oid relid = PG_GETARG_OID(1); - text *result; - int prettyFlags; - - prettyFlags = PRETTYFLAG_INDENT; - - result = pg_get_expr_worker(expr, relid, prettyFlags); - if (result) - PG_RETURN_TEXT_P(result); - else - PG_RETURN_NULL(); -} - -Datum -pg_get_expr_ext(PG_FUNCTION_ARGS) { text *expr = PG_GETARG_TEXT_PP(0); Oid relid = PG_GETARG_OID(1); diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat index e610a6213ec..df43469be3d 100644 --- a/src/include/catalog/pg_proc.dat +++ b/src/include/catalog/pg_proc.dat @@ -4006,9 +4006,6 @@ { oid => '1662', descr => 'trigger description', proname => 'pg_get_triggerdef', provolatile => 's', prorettype => 'text', proargtypes => 'oid', prosrc => 'pg_get_triggerdef' }, -{ oid => '1716', descr => 'deparse an encoded expression', - proname => 'pg_get_expr', provolatile => 's', prorettype => 'text', - proargtypes => 'pg_node_tree oid', prosrc => 'pg_get_expr' }, { oid => '1665', descr => 'name of sequence for a serial column', proname => 'pg_get_serial_sequence', provolatile => 's', prorettype => 'text', proargtypes => 'text text', prosrc => 'pg_get_serial_sequence' }, @@ -8605,9 +8602,11 @@ proargmodes => '{i,v}', proargdefaults => '{NULL}', prosrc => 'pg_get_database_ddl' }, { oid => '2509', - descr => 'deparse an encoded expression with pretty-print option', + descr => 'deparse an encoded expression', proname => 'pg_get_expr', provolatile => 's', prorettype => 'text', - proargtypes => 'pg_node_tree oid bool', prosrc => 'pg_get_expr_ext' }, + proargtypes => 'pg_node_tree oid bool', + proargnames => '{expr,relation,pretty}', proargdefaults => '{false}', + prosrc => 'pg_get_expr' }, { oid => '2510', descr => 'get the prepared statements for this session', proname => 'pg_prepared_statement', prorows => '1000', proretset => 't', provolatile => 's', proparallel => 'r', prorettype => 'record', -- 2.53.0 --AcCatzXgbvyipyEy Content-Type: text/plain; charset=us-ascii Content-Disposition: attachment; filename=v8.1-0006-Handle-pg_get_triggerdef-default-args-in-system.patch ^ permalink raw reply [nested|flat] 248+ messages in thread
* [PATCH v1 5/6] Handle pg_get_expr default args in system_functions.sql @ 2025-12-09 19:17 Mark Wong <[email protected]> 0 siblings, 0 replies; 248+ messages in thread From: Mark Wong @ 2025-12-09 19:17 UTC (permalink / raw) Modernize pg_get_expr to use CREATE OR REPLACE FUNCTION to handle the optional pretty argument. --- src/backend/catalog/system_functions.sql | 7 +++++++ src/backend/utils/adt/ruleutils.c | 17 ----------------- src/include/catalog/pg_proc.dat | 5 +---- 3 files changed, 8 insertions(+), 21 deletions(-) diff --git a/src/backend/catalog/system_functions.sql b/src/backend/catalog/system_functions.sql index 1f89dcc7908..81d210a9c45 100644 --- a/src/backend/catalog/system_functions.sql +++ b/src/backend/catalog/system_functions.sql @@ -692,6 +692,13 @@ LANGUAGE INTERNAL PARALLEL SAFE AS 'pg_get_constraintdef'; +CREATE OR REPLACE FUNCTION + pg_get_expr(expr pg_node_tree, relation oid, pretty bool DEFAULT false) +RETURNS TEXT +LANGUAGE INTERNAL +PARALLEL SAFE +AS 'pg_get_expr'; + -- -- The default permissions for functions mean that anyone can execute them. -- A number of functions shouldn't be executable by just anyone, but rather diff --git a/src/backend/utils/adt/ruleutils.c b/src/backend/utils/adt/ruleutils.c index 416144c49f5..9effa02fa2e 100644 --- a/src/backend/utils/adt/ruleutils.c +++ b/src/backend/utils/adt/ruleutils.c @@ -2573,23 +2573,6 @@ decompile_column_index_array(Datum column_index_array, Oid relId, */ Datum pg_get_expr(PG_FUNCTION_ARGS) -{ - text *expr = PG_GETARG_TEXT_PP(0); - Oid relid = PG_GETARG_OID(1); - text *result; - int prettyFlags; - - prettyFlags = PRETTYFLAG_INDENT; - - result = pg_get_expr_worker(expr, relid, prettyFlags); - if (result) - PG_RETURN_TEXT_P(result); - else - PG_RETURN_NULL(); -} - -Datum -pg_get_expr_ext(PG_FUNCTION_ARGS) { text *expr = PG_GETARG_TEXT_PP(0); Oid relid = PG_GETARG_OID(1); diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat index a9431ea4037..10c5286bd7d 100644 --- a/src/include/catalog/pg_proc.dat +++ b/src/include/catalog/pg_proc.dat @@ -3977,9 +3977,6 @@ { oid => '1662', descr => 'trigger description', proname => 'pg_get_triggerdef', provolatile => 's', prorettype => 'text', proargtypes => 'oid', prosrc => 'pg_get_triggerdef' }, -{ oid => '1716', descr => 'deparse an encoded expression', - proname => 'pg_get_expr', provolatile => 's', prorettype => 'text', - proargtypes => 'pg_node_tree oid', prosrc => 'pg_get_expr' }, { oid => '1665', descr => 'name of sequence for a serial column', proname => 'pg_get_serial_sequence', provolatile => 's', prorettype => 'text', proargtypes => 'text text', prosrc => 'pg_get_serial_sequence' }, @@ -8502,7 +8499,7 @@ { oid => '2509', descr => 'deparse an encoded expression with pretty-print option', proname => 'pg_get_expr', provolatile => 's', prorettype => 'text', - proargtypes => 'pg_node_tree oid bool', prosrc => 'pg_get_expr_ext' }, + proargtypes => 'pg_node_tree oid bool', prosrc => 'pg_get_expr' }, { oid => '2510', descr => 'get the prepared statements for this session', proname => 'pg_prepared_statement', prorows => '1000', proretset => 't', provolatile => 's', proparallel => 'r', prorettype => 'record', -- 2.51.2 --IRGsBYp1UN8d6WrT Content-Type: text/plain; charset=us-ascii Content-Disposition: attachment; filename=v1-0006-Handle-pg_get_triggerdef-default-args-in-system_f.patch ^ permalink raw reply [nested|flat] 248+ messages in thread
* [PATCH v5 5/6] Handle pg_get_expr default args in system_functions.sql @ 2025-12-09 19:17 Mark Wong <[email protected]> 0 siblings, 0 replies; 248+ messages in thread From: Mark Wong @ 2025-12-09 19:17 UTC (permalink / raw) Modernize pg_get_expr to use proargdefaults to handle the optional pretty argument. That also means any direct function calls now needs to set the pretty parameter. --- src/backend/commands/tablecmds.c | 5 +++-- src/backend/utils/adt/ruleutils.c | 17 ----------------- src/include/catalog/pg_proc.dat | 7 +++---- 3 files changed, 6 insertions(+), 23 deletions(-) diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 0ce2e81f9c2..fad4202b1ff 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -17694,8 +17694,9 @@ decompile_conbin(HeapTuple contup, TupleDesc tupdesc) if (isnull) elog(ERROR, "null conbin for constraint %u", con->oid); - expr = DirectFunctionCall2(pg_get_expr, attr, - ObjectIdGetDatum(con->conrelid)); + expr = DirectFunctionCall3(pg_get_expr, attr, + ObjectIdGetDatum(con->conrelid), + BoolGetDatum(false)); return TextDatumGetCString(expr); } diff --git a/src/backend/utils/adt/ruleutils.c b/src/backend/utils/adt/ruleutils.c index 1afa2531f30..972f89eafbc 100644 --- a/src/backend/utils/adt/ruleutils.c +++ b/src/backend/utils/adt/ruleutils.c @@ -2932,23 +2932,6 @@ decompile_column_index_array(Datum column_index_array, Oid relId, */ Datum pg_get_expr(PG_FUNCTION_ARGS) -{ - text *expr = PG_GETARG_TEXT_PP(0); - Oid relid = PG_GETARG_OID(1); - text *result; - int prettyFlags; - - prettyFlags = PRETTYFLAG_INDENT; - - result = pg_get_expr_worker(expr, relid, prettyFlags); - if (result) - PG_RETURN_TEXT_P(result); - else - PG_RETURN_NULL(); -} - -Datum -pg_get_expr_ext(PG_FUNCTION_ARGS) { text *expr = PG_GETARG_TEXT_PP(0); Oid relid = PG_GETARG_OID(1); diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat index e148b1ad8e3..f36f4625e50 100644 --- a/src/include/catalog/pg_proc.dat +++ b/src/include/catalog/pg_proc.dat @@ -4000,9 +4000,6 @@ { oid => '1662', descr => 'trigger description', proname => 'pg_get_triggerdef', provolatile => 's', prorettype => 'text', proargtypes => 'oid', prosrc => 'pg_get_triggerdef' }, -{ oid => '1716', descr => 'deparse an encoded expression', - proname => 'pg_get_expr', provolatile => 's', prorettype => 'text', - proargtypes => 'pg_node_tree oid', prosrc => 'pg_get_expr' }, { oid => '1665', descr => 'name of sequence for a serial column', proname => 'pg_get_serial_sequence', provolatile => 's', prorettype => 'text', proargtypes => 'text text', prosrc => 'pg_get_serial_sequence' }, @@ -8595,7 +8592,9 @@ { oid => '2509', descr => 'deparse an encoded expression with pretty-print option', proname => 'pg_get_expr', provolatile => 's', prorettype => 'text', - proargtypes => 'pg_node_tree oid bool', prosrc => 'pg_get_expr_ext' }, + proargtypes => 'pg_node_tree oid bool', + proargnames => '{expr,relation,pretty}', proargdefaults => '{false}', + prosrc => 'pg_get_expr' }, { oid => '2510', descr => 'get the prepared statements for this session', proname => 'pg_prepared_statement', prorows => '1000', proretset => 't', provolatile => 's', proparallel => 'r', prorettype => 'record', -- 2.52.0 --m23X5uHFNxthGTU3 Content-Type: text/plain; charset=us-ascii Content-Disposition: attachment; filename=v5-0006-Handle-pg_get_triggerdef-default-args-in-system_f.patch ^ permalink raw reply [nested|flat] 248+ messages in thread
* [PATCH v46 7/7] Teach snapshot builder to skip transactions running REPACK (CONCURRENTLY). @ 2026-03-17 19:22 Antonin Houska <[email protected]> 0 siblings, 0 replies; 248+ messages in thread From: Antonin Houska @ 2026-03-17 19:22 UTC (permalink / raw) During logical decoding, we need to know if particular transaction performed catalog changes because catalog information is needed to construct heap tuples. To be sure that we have enough information of each transaction, the logical decoding cannot start before all the already running transactions have completed. The problem with REPACK (CONCURRENTLY) is that it has XID assigned and writes WAL records marked with it. Thus if another backend runs REPACK (CONCURRENTLY) and tries to setup the logical decoding, it has to wait for the completion of all the other transactions involved in REPACK (CONCURRENTLY). However, REPACK (CONCURRENTLY) does not perform any catalog changes relevant to logical decoding, so the other backends executing this command can ignore it. This patch implements it by adding information about transactions executing the command to the xl_running_xacts WAL record, and by teaching the snapshot builder to use the information. --- src/backend/access/rmgrdesc/standbydesc.c | 15 ++++- src/backend/access/transam/xlog.c | 2 + src/backend/commands/repack.c | 16 +++++ src/backend/replication/logical/snapbuild.c | 38 ++++++++--- src/backend/storage/ipc/procarray.c | 74 +++++++++++++++++++-- src/backend/storage/ipc/standby.c | 8 ++- src/include/storage/standby.h | 3 + src/include/storage/standbydefs.h | 2 + 8 files changed, 137 insertions(+), 21 deletions(-) diff --git a/src/backend/access/rmgrdesc/standbydesc.c b/src/backend/access/rmgrdesc/standbydesc.c index 0a291354ae2..b96b73d51d3 100644 --- a/src/backend/access/rmgrdesc/standbydesc.c +++ b/src/backend/access/rmgrdesc/standbydesc.c @@ -21,10 +21,11 @@ standby_desc_running_xacts(StringInfo buf, xl_running_xacts *xlrec) { int i; - appendStringInfo(buf, "nextXid %u latestCompletedXid %u oldestRunningXid %u", + appendStringInfo(buf, "nextXid %u latestCompletedXid %u oldestRunningXid %u oldestRunningXidLogical %u", xlrec->nextXid, xlrec->latestCompletedXid, - xlrec->oldestRunningXid); + xlrec->oldestRunningXid, + xlrec->oldestRunningXidLogical); if (xlrec->xcnt > 0) { appendStringInfo(buf, "; %d xacts:", xlrec->xcnt); @@ -41,6 +42,16 @@ standby_desc_running_xacts(StringInfo buf, xl_running_xacts *xlrec) for (i = 0; i < xlrec->subxcnt; i++) appendStringInfo(buf, " %u", xlrec->xids[xlrec->xcnt + i]); } + + if (xlrec->xcnt_repack > 0) + { + TransactionId *xids_repack; + + appendStringInfo(buf, "; %d xacts_repack:", xlrec->xcnt_repack); + xids_repack = xlrec->xids + xlrec->xcnt + xlrec->subxcnt; + for (i = 0; i < xlrec->xcnt_repack; i++) + appendStringInfo(buf, " %u", xids_repack[i]); + } } void diff --git a/src/backend/access/transam/xlog.c b/src/backend/access/transam/xlog.c index f5c9a34374d..d050b0b1444 100644 --- a/src/backend/access/transam/xlog.c +++ b/src/backend/access/transam/xlog.c @@ -5912,6 +5912,7 @@ StartupXLOG(void) * subxids are listed with their parent prepared transactions. */ running.xcnt = nxids; + running.xcnt_repack = 0; running.subxcnt = 0; running.subxid_status = SUBXIDS_IN_SUBTRANS; running.nextXid = XidFromFullTransactionId(checkPoint.nextXid); @@ -8477,6 +8478,7 @@ xlog_redo(XLogReaderState *record) * with their parent prepared transactions. */ running.xcnt = nxids; + running.xcnt_repack = 0; running.subxcnt = 0; running.subxid_status = SUBXIDS_IN_SUBTRANS; running.nextXid = XidFromFullTransactionId(checkPoint.nextXid); diff --git a/src/backend/commands/repack.c b/src/backend/commands/repack.c index 21ab81c6f7f..42165c5552e 100644 --- a/src/backend/commands/repack.c +++ b/src/backend/commands/repack.c @@ -988,6 +988,22 @@ rebuild_relation(Relation OldHeap, Relation index, bool verbose, if (concurrent) { + /* + * Do not let other backends wait for our completion during their + * setup of logical replication. Unlike logical replication publisher, + * we will have XID assigned, so the other backends - whether + * walsenders involved in logical replication or regular backends + * executing also REPACK (CONCURRENTLY) - would have to wait for our + * completion before they can build their initial snapshot. It is + * o.k. for any decoding backend to ignore us because we do not change + * tuple descriptor of any table, and the data changes we write should + * not be decoded by other backends. + */ + LWLockAcquire(ProcArrayLock, LW_EXCLUSIVE); + MyProc->statusFlags |= PROC_IN_CONCURRENT_REPACK; + ProcGlobal->statusFlags[MyProc->pgxactoff] = MyProc->statusFlags; + LWLockRelease(ProcArrayLock); + /* * The worker needs to be member of the locking group we're the leader * of. We ought to become the leader before the worker starts. The diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index 9cf499ce7c6..fbdd4600a2b 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -1172,7 +1172,7 @@ SnapBuildProcessRunningXacts(SnapBuild *builder, XLogRecPtr lsn, xl_running_xact * xmin, which looks odd but is correct and actually more efficient, since * we hit fast paths in heapam_visibility.c. */ - builder->xmin = running->oldestRunningXid; + builder->xmin = running->oldestRunningXidLogical; /* Remove transactions we don't need to keep track off anymore */ SnapBuildPurgeOlderTxn(builder); @@ -1188,9 +1188,9 @@ SnapBuildProcessRunningXacts(SnapBuild *builder, XLogRecPtr lsn, xl_running_xact */ xmin = ReorderBufferGetOldestXmin(builder->reorder); if (xmin == InvalidTransactionId) - xmin = running->oldestRunningXid; + xmin = running->oldestRunningXidLogical; elog(DEBUG3, "xmin: %u, xmax: %u, oldest running: %u, oldest xmin: %u", - builder->xmin, builder->xmax, running->oldestRunningXid, xmin); + builder->xmin, builder->xmax, running->oldestRunningXidLogical, xmin); LogicalIncreaseXminForSlot(lsn, xmin); /* @@ -1275,14 +1275,14 @@ SnapBuildFindSnapshot(SnapBuild *builder, XLogRecPtr lsn, xl_running_xacts *runn * have all necessary catalog rows anymore. */ if (TransactionIdIsNormal(builder->initial_xmin_horizon) && - NormalTransactionIdPrecedes(running->oldestRunningXid, + NormalTransactionIdPrecedes(running->oldestRunningXidLogical, builder->initial_xmin_horizon)) { ereport(DEBUG1, errmsg_internal("skipping snapshot at %X/%08X while building logical decoding snapshot, xmin horizon too low", LSN_FORMAT_ARGS(lsn)), errdetail_internal("initial xmin horizon of %u vs the snapshot's %u", - builder->initial_xmin_horizon, running->oldestRunningXid)); + builder->initial_xmin_horizon, running->oldestRunningXidLogical)); SnapBuildWaitSnapshot(running, builder->initial_xmin_horizon); @@ -1299,7 +1299,7 @@ SnapBuildFindSnapshot(SnapBuild *builder, XLogRecPtr lsn, xl_running_xacts *runn * NB: We might have already started to incrementally assemble a snapshot, * so we need to be careful to deal with that. */ - if (running->oldestRunningXid == running->nextXid) + if (running->oldestRunningXidLogical == running->nextXid) { if (!XLogRecPtrIsValid(builder->start_decoding_at) || builder->start_decoding_at <= lsn) @@ -1378,14 +1378,14 @@ SnapBuildFindSnapshot(SnapBuild *builder, XLogRecPtr lsn, xl_running_xacts *runn /* * c) transition from BUILDING_SNAPSHOT to FULL_SNAPSHOT. * - * In BUILDING_SNAPSHOT state, and this xl_running_xacts' oldestRunningXid + * In BUILDING_SNAPSHOT state, and this xl_running_xacts' oldestRunningXidLogical * is >= than nextXid from when we switched to BUILDING_SNAPSHOT. This * means all transactions starting afterwards have enough information to * be decoded. Switch to FULL_SNAPSHOT. */ else if (builder->state == SNAPBUILD_BUILDING_SNAPSHOT && TransactionIdPrecedesOrEquals(builder->next_phase_at, - running->oldestRunningXid)) + running->oldestRunningXidLogical)) { builder->state = SNAPBUILD_FULL_SNAPSHOT; builder->next_phase_at = running->nextXid; @@ -1402,14 +1402,14 @@ SnapBuildFindSnapshot(SnapBuild *builder, XLogRecPtr lsn, xl_running_xacts *runn /* * c) transition from FULL_SNAPSHOT to CONSISTENT. * - * In FULL_SNAPSHOT state, and this xl_running_xacts' oldestRunningXid is + * In FULL_SNAPSHOT state, and this xl_running_xacts' oldestRunningXidLogical is * >= than nextXid from when we switched to FULL_SNAPSHOT. This means all * transactions that are currently in progress have a catalog snapshot, * and all their changes have been collected. Switch to CONSISTENT. */ else if (builder->state == SNAPBUILD_FULL_SNAPSHOT && TransactionIdPrecedesOrEquals(builder->next_phase_at, - running->oldestRunningXid)) + running->oldestRunningXidLogical)) { builder->state = SNAPBUILD_CONSISTENT; builder->next_phase_at = InvalidTransactionId; @@ -1459,6 +1459,24 @@ SnapBuildWaitSnapshot(xl_running_xacts *running, TransactionId cutoff) if (TransactionIdFollows(xid, cutoff)) continue; + /* Do not wait for transactions running REPACK (CONCURRENTLY). */ + if (running->xcnt_repack > 0) + { + TransactionId *xids_repack; + int i; + + xids_repack = running->xids + running->xcnt + running->subxcnt; + + for (i = 0; i < running->xcnt_repack; i++) + { + if (xid == xids_repack[i]) + break; + } + /* Found? */ + if (i < running->xcnt_repack) + continue; + } + XactLockTableWait(xid, NULL, NULL, XLTW_None); } diff --git a/src/backend/storage/ipc/procarray.c b/src/backend/storage/ipc/procarray.c index cc207cb56e3..6dd4fa7dcc0 100644 --- a/src/backend/storage/ipc/procarray.c +++ b/src/backend/storage/ipc/procarray.c @@ -2643,15 +2643,24 @@ GetRunningTransactionData(void) RunningTransactions CurrentRunningXacts = &CurrentRunningXactsData; TransactionId latestCompletedXid; TransactionId oldestRunningXid; + TransactionId oldestRunningXidLogical; TransactionId oldestDatabaseRunningXid; TransactionId *xids; int index; - int count; + int count, count_repack; int subcount; bool suboverflowed; + TransactionId *xids_repack = NULL; + bool logical_decoding_enabled = IsLogicalDecodingEnabled(); Assert(!RecoveryInProgress()); + /* + * TODO Consider a GUC to reserve certain amount of replication slots for + * REPACK (CONCURRENTLY) and using it here. + */ +#define MAX_REPACK_XIDS 16 + /* * Allocating space for maxProcs xids is usually overkill; numProcs would * be sufficient. But it seems better to do the malloc while not holding @@ -2663,11 +2672,14 @@ GetRunningTransactionData(void) */ if (CurrentRunningXacts->xids == NULL) { + /* FIXME probably fails if logical decoding is enable on-the-fly */ + int nrepack = logical_decoding_enabled ? MAX_REPACK_XIDS : 0; + /* * First call */ CurrentRunningXacts->xids = (TransactionId *) - malloc(TOTAL_MAX_CACHED_SUBXIDS * sizeof(TransactionId)); + malloc((TOTAL_MAX_CACHED_SUBXIDS + nrepack) * sizeof(TransactionId)); if (CurrentRunningXacts->xids == NULL) ereport(ERROR, (errcode(ERRCODE_OUT_OF_MEMORY), @@ -2676,7 +2688,10 @@ GetRunningTransactionData(void) xids = CurrentRunningXacts->xids; - count = subcount = 0; + if (logical_decoding_enabled) + xids_repack = palloc_array(TransactionId, MAX_REPACK_XIDS); + + count = subcount = count_repack = 0; suboverflowed = false; /* @@ -2688,7 +2703,7 @@ GetRunningTransactionData(void) latestCompletedXid = XidFromFullTransactionId(TransamVariables->latestCompletedXid); - oldestDatabaseRunningXid = oldestRunningXid = + oldestDatabaseRunningXid = oldestRunningXid = oldestRunningXidLogical = XidFromFullTransactionId(TransamVariables->nextXid); /* @@ -2697,6 +2712,8 @@ GetRunningTransactionData(void) for (index = 0; index < arrayP->numProcs; index++) { TransactionId xid; + int pgprocno; + PGPROC *proc; /* Fetch xid just once - see GetNewTransactionId */ xid = UINT32_ACCESS_ONCE(other_xids[index]); @@ -2716,6 +2733,21 @@ GetRunningTransactionData(void) if (TransactionIdPrecedes(xid, oldestRunningXid)) oldestRunningXid = xid; + if (logical_decoding_enabled && + TransactionIdPrecedes(xid, oldestRunningXidLogical)) + { + /* + * Backends running REPACK concurrently need to be excluded from + * oldestRunningXidLogical, otherwise the snapshot builder cannot + * proceed in building the initial snapshot. + */ + pgprocno = arrayP->pgprocnos[index]; + proc = &allProcs[pgprocno]; + + if ((proc->statusFlags & PROC_IN_CONCURRENT_REPACK) == 0) + oldestRunningXidLogical = xid; + } + /* * Also, update the oldest running xid within the current database. As * fetching pgprocno and PGPROC could cause cache misses, we do cheap @@ -2723,8 +2755,8 @@ GetRunningTransactionData(void) */ if (TransactionIdPrecedes(xid, oldestDatabaseRunningXid)) { - int pgprocno = arrayP->pgprocnos[index]; - PGPROC *proc = &allProcs[pgprocno]; + pgprocno = arrayP->pgprocnos[index]; + proc = &allProcs[pgprocno]; if (proc->databaseId == MyDatabaseId) oldestDatabaseRunningXid = xid; @@ -2742,6 +2774,19 @@ GetRunningTransactionData(void) */ xids[count++] = xid; + + /* + * Collect XIDSs of transactions running REPACK (CONCURRENTLY). + */ + if (logical_decoding_enabled && + count_repack < MAX_REPACK_XIDS) + { + pgprocno = arrayP->pgprocnos[index]; + proc = &allProcs[pgprocno]; + + if (proc->statusFlags & PROC_IN_CONCURRENT_REPACK) + xids_repack[count_repack++] = xid; + } } /* @@ -2782,6 +2827,19 @@ GetRunningTransactionData(void) } } + /* + * Append the XIDs running REPACK (CONCURRENTLY), if any. + * + * XXX Should we sort the array and use bsearch() when using it? + */ + if (count_repack > 0) + { + for (int i = 0; i < count_repack; i++) + xids[count++] = xids_repack[i]; + } + if (xids_repack) + pfree(xids_repack); + /* * It's important *not* to include the limits set by slots here because * snapbuild.c uses oldestRunningXid to manage its xmin horizon. If those @@ -2791,11 +2849,13 @@ GetRunningTransactionData(void) * increases if slots do. */ - CurrentRunningXacts->xcnt = count - subcount; + CurrentRunningXacts->xcnt = count - subcount - count_repack; CurrentRunningXacts->subxcnt = subcount; + CurrentRunningXacts->xcnt_repack = count_repack; CurrentRunningXacts->subxid_status = suboverflowed ? SUBXIDS_IN_SUBTRANS : SUBXIDS_IN_ARRAY; CurrentRunningXacts->nextXid = XidFromFullTransactionId(TransamVariables->nextXid); CurrentRunningXacts->oldestRunningXid = oldestRunningXid; + CurrentRunningXacts->oldestRunningXidLogical = oldestRunningXidLogical; CurrentRunningXacts->oldestDatabaseRunningXid = oldestDatabaseRunningXid; CurrentRunningXacts->latestCompletedXid = latestCompletedXid; diff --git a/src/backend/storage/ipc/standby.c b/src/backend/storage/ipc/standby.c index de9092fdf5b..fd3e4fe31f3 100644 --- a/src/backend/storage/ipc/standby.c +++ b/src/backend/storage/ipc/standby.c @@ -1189,6 +1189,7 @@ standby_redo(XLogReaderState *record) RunningTransactionsData running; running.xcnt = xlrec->xcnt; + running.xcnt_repack = xlrec->xcnt_repack; running.subxcnt = xlrec->subxcnt; running.subxid_status = xlrec->subxid_overflow ? SUBXIDS_MISSING : SUBXIDS_IN_ARRAY; running.nextXid = xlrec->nextXid; @@ -1359,10 +1360,12 @@ LogCurrentRunningXacts(RunningTransactions CurrRunningXacts) XLogRecPtr recptr; xlrec.xcnt = CurrRunningXacts->xcnt; + xlrec.xcnt_repack = CurrRunningXacts->xcnt_repack; xlrec.subxcnt = CurrRunningXacts->subxcnt; xlrec.subxid_overflow = (CurrRunningXacts->subxid_status != SUBXIDS_IN_ARRAY); xlrec.nextXid = CurrRunningXacts->nextXid; xlrec.oldestRunningXid = CurrRunningXacts->oldestRunningXid; + xlrec.oldestRunningXidLogical = CurrRunningXacts->oldestRunningXidLogical; xlrec.latestCompletedXid = CurrRunningXacts->latestCompletedXid; /* Header */ @@ -1371,9 +1374,10 @@ LogCurrentRunningXacts(RunningTransactions CurrRunningXacts) XLogRegisterData(&xlrec, MinSizeOfXactRunningXacts); /* array of TransactionIds */ - if (xlrec.xcnt > 0) + if (xlrec.xcnt + xlrec.xcnt_repack > 0) XLogRegisterData(CurrRunningXacts->xids, - (xlrec.xcnt + xlrec.subxcnt) * sizeof(TransactionId)); + (xlrec.xcnt + xlrec.xcnt_repack + xlrec.subxcnt) * + sizeof(TransactionId)); recptr = XLogInsert(RM_STANDBY_ID, XLOG_RUNNING_XACTS); diff --git a/src/include/storage/standby.h b/src/include/storage/standby.h index 6a314c693cd..9e6e7b18786 100644 --- a/src/include/storage/standby.h +++ b/src/include/storage/standby.h @@ -127,10 +127,13 @@ typedef enum typedef struct RunningTransactionsData { int xcnt; /* # of xact ids in xids[] */ + int xcnt_repack; /* # of xacts running REPACK + * (CONCURRENTLY). */ int subxcnt; /* # of subxact ids in xids[] */ subxids_array_status subxid_status; TransactionId nextXid; /* xid from TransamVariables->nextXid */ TransactionId oldestRunningXid; /* *not* oldestXmin */ + TransactionId oldestRunningXidLogical; TransactionId oldestDatabaseRunningXid; /* same as above, but within the * current database */ TransactionId latestCompletedXid; /* so we can set xmax */ diff --git a/src/include/storage/standbydefs.h b/src/include/storage/standbydefs.h index 231d251fd51..edad609fa9a 100644 --- a/src/include/storage/standbydefs.h +++ b/src/include/storage/standbydefs.h @@ -47,10 +47,12 @@ typedef struct xl_standby_locks typedef struct xl_running_xacts { int xcnt; /* # of xact ids in xids[] */ + int xcnt_repack; /* # of xacts running REPACK (CONCURRENTLY) */ int subxcnt; /* # of subxact ids in xids[] */ bool subxid_overflow; /* snapshot overflowed, subxids missing */ TransactionId nextXid; /* xid from TransamVariables->nextXid */ TransactionId oldestRunningXid; /* *not* oldestXmin */ + TransactionId oldestRunningXidLogical; TransactionId latestCompletedXid; /* so we can set xmax */ TransactionId xids[FLEXIBLE_ARRAY_MEMBER]; -- 2.47.3 --mdsv5bdgfjjj6d77-- ^ permalink raw reply [nested|flat] 248+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 248+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 248+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 248+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 248+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 248+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 248+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 248+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 248+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 248+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 248+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 248+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 248+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 248+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 248+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 248+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 248+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 248+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 248+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 248+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 248+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 248+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 248+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 248+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 248+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 248+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 248+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 248+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 248+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 248+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 248+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 248+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 248+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 248+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 248+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 248+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 248+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 248+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 248+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 248+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 248+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 248+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 248+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 248+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 248+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 248+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 248+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 248+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 248+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 248+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 248+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 248+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 248+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 248+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 248+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 248+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 248+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 248+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 248+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 248+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 248+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 248+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 248+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 248+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 248+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 248+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 248+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 248+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 248+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 248+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 248+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 248+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 248+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 248+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 248+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 248+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 248+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 248+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 248+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 248+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 248+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 248+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 248+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 248+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 248+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 248+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 248+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 248+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 248+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 248+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 248+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 248+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 248+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 248+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 248+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 248+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 248+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 248+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 248+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 248+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 248+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 248+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 248+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 248+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 248+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 248+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 248+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 248+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 248+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 248+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 248+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 248+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 248+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 248+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 248+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 248+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 248+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 248+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 248+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 248+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 248+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 248+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 248+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 248+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 248+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 248+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 248+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 248+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 248+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 248+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 248+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 248+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 248+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 248+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 248+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 248+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 248+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 248+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 248+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 248+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 248+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 248+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 248+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 248+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 248+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 248+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 248+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 248+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 248+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 248+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 248+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 248+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 248+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 248+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 248+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 248+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 248+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 248+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 248+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 248+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 248+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 248+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 248+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 248+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 248+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 248+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 248+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 248+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 248+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 248+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 248+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 248+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 248+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 248+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 248+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 248+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 248+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 248+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 248+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 248+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 248+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 248+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 248+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 248+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 248+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 248+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 248+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 248+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 248+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 248+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 248+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 248+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 248+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 248+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 248+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 248+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 248+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 248+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 248+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 248+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 248+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 248+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 248+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 248+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 248+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 248+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 248+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 248+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 248+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 248+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 248+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 248+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 248+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 248+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 248+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 248+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 248+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 248+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 248+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 248+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 248+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 248+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 248+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 248+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 248+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 248+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 248+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 248+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 248+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 248+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 248+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 248+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 248+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 248+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 248+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 248+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 248+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 248+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 248+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 248+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 248+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 248+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 248+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 248+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 248+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 248+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 248+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 248+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 248+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 248+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 248+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 248+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 248+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 248+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 248+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 248+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 248+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 248+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 248+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 248+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 248+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 248+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 248+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 248+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 248+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 248+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 248+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 248+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 248+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 248+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 248+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 248+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 248+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 248+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 248+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 248+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 248+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 248+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 248+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 248+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 248+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 248+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 248+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 248+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 248+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 248+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 248+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 248+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 248+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 248+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 248+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 248+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 248+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 248+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 248+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 248+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 248+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 248+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 248+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 248+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 248+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 248+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 248+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 248+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 248+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 248+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 248+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 248+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 248+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 248+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 248+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 248+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 248+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 248+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 248+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 248+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 248+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 248+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 248+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 248+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 248+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 248+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 248+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 248+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 248+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 248+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 248+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 248+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 248+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 248+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 248+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 248+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 248+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 248+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 248+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 248+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 248+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 248+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 248+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 248+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 248+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 248+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 248+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 248+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 248+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 248+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 248+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 248+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 248+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 248+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 248+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 248+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 248+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 248+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 248+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 248+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 248+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 248+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 248+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 248+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 248+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 248+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 248+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 248+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 248+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 248+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 248+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 248+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 248+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 248+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 248+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 248+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 248+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 248+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 248+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 248+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 248+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 248+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 248+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 248+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 248+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 248+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 248+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 248+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 248+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 248+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 248+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 248+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 248+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 248+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 248+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 248+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 248+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 248+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 248+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 248+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 248+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 248+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 248+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 248+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 248+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 248+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 248+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 248+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 248+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 248+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 248+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 248+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 248+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 248+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 248+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 248+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 248+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 248+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 248+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 248+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 248+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 248+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 248+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 248+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 248+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 248+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 248+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 248+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 248+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 248+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 248+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 248+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 248+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 248+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 248+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 248+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 248+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 248+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 248+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 248+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 248+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 248+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 248+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 248+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 248+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 248+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 248+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 248+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 248+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 248+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 248+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 248+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 248+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 248+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 248+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 248+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 248+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 248+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 248+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 248+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 248+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 248+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 248+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 248+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 248+ messages in thread
end of thread, other threads:[~2026-05-12 10:27 UTC | newest] Thread overview: 248+ messages (download: mbox mbox.gz follow: Atom feed) -- links below jump to the message on this page -- 2020-03-21 01:47 [PATCH v1 1/2] Report wait event for cost-based vacuum delay Justin Pryzby <[email protected]> 2025-12-09 19:17 [PATCH v2 5/6] Handle pg_get_expr default args in system_functions.sql Mark Wong <[email protected]> 2025-12-09 19:17 [PATCH v7 5/6] Handle pg_get_expr default args in system_functions.sql Mark Wong <[email protected]> 2025-12-09 19:17 [PATCH v5 5/6] Handle pg_get_expr default args in system_functions.sql Mark Wong <[email protected]> 2025-12-09 19:17 [PATCH v8 5/6] Handle pg_get_expr default args in system_functions.sql Mark Wong <[email protected]> 2025-12-09 19:17 [PATCH v2 5/6] Handle pg_get_expr default args in system_functions.sql Mark Wong <[email protected]> 2025-12-09 19:17 [PATCH v4 5/6] Handle pg_get_expr default args in system_functions.sql Mark Wong <[email protected]> 2025-12-09 19:17 [PATCH v8 5/6] Handle pg_get_expr default args in system_functions.sql Mark Wong <[email protected]> 2025-12-09 19:17 [PATCH v3 6/7] Handle pg_get_expr default args in system_functions.sql Mark Wong <[email protected]> 2025-12-09 19:17 [PATCH v4 5/6] Handle pg_get_expr default args in system_functions.sql Mark Wong <[email protected]> 2025-12-09 19:17 [PATCH v7 5/6] Handle pg_get_expr default args in system_functions.sql Mark Wong <[email protected]> 2025-12-09 19:17 [PATCH v3 6/7] Handle pg_get_expr default args in system_functions.sql Mark Wong <[email protected]> 2025-12-09 19:17 [PATCH v8.1 5/6] Handle pg_get_expr default args in system_functions.sql Mark Wong <[email protected]> 2025-12-09 19:17 [PATCH v1 5/6] Handle pg_get_expr default args in system_functions.sql Mark Wong <[email protected]> 2025-12-09 19:17 [PATCH v8.1 5/6] Handle pg_get_expr default args in system_functions.sql Mark Wong <[email protected]> 2025-12-09 19:17 [PATCH v1 5/6] Handle pg_get_expr default args in system_functions.sql Mark Wong <[email protected]> 2025-12-09 19:17 [PATCH v5 5/6] Handle pg_get_expr default args in system_functions.sql Mark Wong <[email protected]> 2026-03-17 19:22 [PATCH v46 7/7] Teach snapshot builder to skip transactions running REPACK (CONCURRENTLY). Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]>
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