agora inbox for [email protected]help / color / mirror / Atom feed
[PATCH v1 1/2] Report wait event for cost-based vacuum delay 143+ 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; 143+ 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] 143+ 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; 143+ 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] 143+ 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; 143+ 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] 143+ 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; 143+ 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] 143+ 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; 143+ 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] 143+ 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; 143+ 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] 143+ 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; 143+ 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] 143+ 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; 143+ 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] 143+ 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; 143+ 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] 143+ 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; 143+ 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] 143+ 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; 143+ 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] 143+ 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; 143+ 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] 143+ 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; 143+ 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] 143+ 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; 143+ 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] 143+ 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; 143+ 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] 143+ 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; 143+ 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] 143+ 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; 143+ 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] 143+ messages in thread
* [PATCH v51 08/10] Introduce an option to make logical replication database specific. @ 2026-04-03 10:34 Antonin Houska <[email protected]> 0 siblings, 0 replies; 143+ messages in thread From: Antonin Houska @ 2026-04-03 10:34 UTC (permalink / raw) By default, the logical decoding assumes access to shared catalogs, so the snapshot builder needs to consider cluster-wide XIDs during startup. That in turn means that, if any transaction is already running (and has XID assigned), the snapshot builder needs to wait for its completion, as it does not know if that transaction performed catalog changes earlier. Possible problem with this concept is that if REPACK (CONCURRENTLY) is running in some database, backends running the same command in other databases get stuck until the first one has committed. Thus only as single backend in the cluster can run REPACK (CONCURRENTLY) at any time. Likewise, REPACK (CONCURRENTLY) can block walsenders starting on behalf of subscriptions throughout the cluster. This patch introduces the possibility for a backend to declare that its output plugin does not use shared catalogs (i.e. catalogs that can be changed by transactions running in other databases in the cluster). In that case, no snapshot the backend will use during the decoding needs to contain information about transactions running in other databases. Thus the snapshot builder only needs to wait for completion of transactions in the current database. Currently we only use this option in the REPACK background worker. It could possibly be used in walsender involved in logical replication too, however that would need thorough analysis of its output plugin. The patch bumps WAL version number, due to a new field in xl_running_xacts. --- contrib/pg_visibility/pg_visibility.c | 4 ++-- src/backend/access/index/genam.c | 18 ++++++++++++++++ src/backend/access/rmgrdesc/standbydesc.c | 2 ++ src/backend/access/transam/xlog.c | 2 +- src/backend/access/transam/xlogfuncs.c | 2 +- src/backend/commands/repack_worker.c | 8 +++++++ src/backend/postmaster/bgwriter.c | 2 +- src/backend/replication/logical/snapbuild.c | 10 ++++++++- src/backend/replication/slot.c | 12 +++++++++-- src/backend/storage/ipc/procarray.c | 23 ++++++++++++++++++++- src/backend/storage/ipc/standby.c | 14 +++++++++++-- src/include/access/genam.h | 8 +++++++ src/include/access/xlog_internal.h | 2 +- src/include/storage/procarray.h | 2 +- src/include/storage/standby.h | 3 ++- src/include/storage/standbydefs.h | 1 + 16 files changed, 99 insertions(+), 14 deletions(-) diff --git a/contrib/pg_visibility/pg_visibility.c b/contrib/pg_visibility/pg_visibility.c index dfab0b64cf5..d564bd2a00c 100644 --- a/contrib/pg_visibility/pg_visibility.c +++ b/contrib/pg_visibility/pg_visibility.c @@ -621,7 +621,7 @@ GetStrictOldestNonRemovableTransactionId(Relation rel) else if (rel == NULL || rel->rd_rel->relisshared) { /* Shared relation: take into account all running xids */ - runningTransactions = GetRunningTransactionData(); + runningTransactions = GetRunningTransactionData(InvalidOid); LWLockRelease(ProcArrayLock); LWLockRelease(XidGenLock); return runningTransactions->oldestRunningXid; @@ -632,7 +632,7 @@ GetStrictOldestNonRemovableTransactionId(Relation rel) * Normal relation: take into account xids running within the current * database */ - runningTransactions = GetRunningTransactionData(); + runningTransactions = GetRunningTransactionData(InvalidOid); LWLockRelease(ProcArrayLock); LWLockRelease(XidGenLock); return runningTransactions->oldestDatabaseRunningXid; diff --git a/src/backend/access/index/genam.c b/src/backend/access/index/genam.c index 1408989c568..df092dc999a 100644 --- a/src/backend/access/index/genam.c +++ b/src/backend/access/index/genam.c @@ -37,6 +37,14 @@ #include "utils/ruleutils.h" #include "utils/snapmgr.h" +/* + * If a backend is going to do logical decoding and if the output plugin does + * not need to access shared catalogs, setting this variable to false can make + * the decoding startup faster. In particular, the backend will not need to + * wait for completion of already running transactions in other databases. + */ +bool accessSharedCatalogsInDecoding = true; + /* ---------------------------------------------------------------- * general access method routines @@ -394,6 +402,16 @@ systable_beginscan(Relation heapRelation, SysScanDesc sysscan; Relation irel; + /* + * If this backend promised that it won't access shared catalogs during + * logical decoding, this seems to be the right place to check. + * + * XXX Should this be ereport(ERROR) ? + */ + Assert(!HistoricSnapshotActive() || + accessSharedCatalogsInDecoding || + !heapRelation->rd_rel->relisshared); + if (indexOK && !IgnoreSystemIndexes && !ReindexIsProcessingIndex(indexId)) diff --git a/src/backend/access/rmgrdesc/standbydesc.c b/src/backend/access/rmgrdesc/standbydesc.c index 0a291354ae2..685d1bdb024 100644 --- a/src/backend/access/rmgrdesc/standbydesc.c +++ b/src/backend/access/rmgrdesc/standbydesc.c @@ -41,6 +41,8 @@ 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]); } + + appendStringInfo(buf, "; dbid: %u", xlrec->dbid); } void diff --git a/src/backend/access/transam/xlog.c b/src/backend/access/transam/xlog.c index 2c1c6f88b74..8da8eff93e4 100644 --- a/src/backend/access/transam/xlog.c +++ b/src/backend/access/transam/xlog.c @@ -7336,7 +7336,7 @@ CreateCheckPoint(int flags) * recovery we don't need to write running xact data. */ if (!shutdown && XLogStandbyInfoActive()) - LogStandbySnapshot(); + LogStandbySnapshot(InvalidOid); START_CRIT_SECTION(); diff --git a/src/backend/access/transam/xlogfuncs.c b/src/backend/access/transam/xlogfuncs.c index 65bbaeda59c..0f5979691e6 100644 --- a/src/backend/access/transam/xlogfuncs.c +++ b/src/backend/access/transam/xlogfuncs.c @@ -245,7 +245,7 @@ pg_log_standby_snapshot(PG_FUNCTION_ARGS) (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE), errmsg("pg_log_standby_snapshot() can only be used if \"wal_level\" >= \"replica\""))); - recptr = LogStandbySnapshot(); + recptr = LogStandbySnapshot(InvalidOid); /* * As a convenience, return the WAL location of the last inserted record diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c85166ba849..ff34e246469 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -16,6 +16,7 @@ */ #include "postgres.h" +#include "access/genam.h" #include "access/table.h" #include "access/xlog_internal.h" #include "access/xlogutils.h" @@ -237,6 +238,13 @@ repack_setup_logical_decoding(Oid relid) EnsureLogicalDecodingEnabled(); + /* + * By declaring that our output plugin does not need shared catalogs, we + * avoid waiting for completion of transactions running in other databases + * than the one we're connected to. + */ + accessSharedCatalogsInDecoding = false; + /* * Neither prepare_write nor do_write callback nor update_progress is * useful for us. diff --git a/src/backend/postmaster/bgwriter.c b/src/backend/postmaster/bgwriter.c index 1d8947774a9..a30de4262eb 100644 --- a/src/backend/postmaster/bgwriter.c +++ b/src/backend/postmaster/bgwriter.c @@ -289,7 +289,7 @@ BackgroundWriterMain(const void *startup_data, size_t startup_data_len) if (now >= timeout && last_snapshot_lsn <= GetLastImportantRecPtr()) { - last_snapshot_lsn = LogStandbySnapshot(); + last_snapshot_lsn = LogStandbySnapshot(InvalidOid); last_snapshot_ts = now; } } diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c index b4269a3b102..2e3926e1d13 100644 --- a/src/backend/replication/logical/snapbuild.c +++ b/src/backend/replication/logical/snapbuild.c @@ -125,6 +125,7 @@ #include <sys/stat.h> #include <unistd.h> +#include "access/genam.h" #include "access/heapam_xlog.h" #include "access/transam.h" #include "access/xact.h" @@ -1465,7 +1466,14 @@ SnapBuildWaitSnapshot(xl_running_xacts *running, TransactionId cutoff) */ if (!RecoveryInProgress()) { - LogStandbySnapshot(); + Oid dbid; + + /* + * Only consider transactions of the current database if our plugin is + * not supposed to access shared catalogs. + */ + dbid = accessSharedCatalogsInDecoding ? InvalidOid : MyDatabaseId; + LogStandbySnapshot(dbid); } } diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c index a9092fc2382..d553bd5dbff 100644 --- a/src/backend/replication/slot.c +++ b/src/backend/replication/slot.c @@ -39,6 +39,7 @@ #include <unistd.h> #include <sys/stat.h> +#include "access/genam.h" #include "access/transam.h" #include "access/xlog_internal.h" #include "access/xlogrecovery.h" @@ -1760,9 +1761,16 @@ ReplicationSlotReserveWal(void) if (!RecoveryInProgress() && SlotIsLogical(slot)) { XLogRecPtr flushptr; + Oid dbid; - /* make sure we have enough information to start */ - flushptr = LogStandbySnapshot(); + /* + * Make sure we have enough information to start. + * + * Only consider transactions of the current database if our plugin is + * not supposed to access shared catalogs. + */ + dbid = accessSharedCatalogsInDecoding ? InvalidOid : MyDatabaseId; + flushptr = LogStandbySnapshot(dbid); /* and make sure it's fsynced to disk */ XLogFlush(flushptr); diff --git a/src/backend/storage/ipc/procarray.c b/src/backend/storage/ipc/procarray.c index cc207cb56e3..92ed34128e5 100644 --- a/src/backend/storage/ipc/procarray.c +++ b/src/backend/storage/ipc/procarray.c @@ -2631,9 +2631,11 @@ ProcArrayInstallRestoredXmin(TransactionId xmin, PGPROC *proc) * * Note that if any transaction has overflowed its cached subtransactions * then there is no real need include any subtransactions. + * + * If 'dbid' is valid, only gather transactions running in that database. */ RunningTransactions -GetRunningTransactionData(void) +GetRunningTransactionData(Oid dbid) { /* result workspace */ static RunningTransactionsData CurrentRunningXactsData; @@ -2708,6 +2710,18 @@ GetRunningTransactionData(void) if (!TransactionIdIsValid(xid)) continue; + /* + * Filter by database OID if requested. + */ + if (OidIsValid(dbid)) + { + int pgprocno = arrayP->pgprocnos[index]; + PGPROC *proc = &allProcs[pgprocno]; + + if (proc->databaseId != dbid) + continue; + } + /* * Be careful not to exclude any xids before calculating the values of * oldestRunningXid and suboverflowed, since these are used to clean @@ -2758,6 +2772,12 @@ GetRunningTransactionData(void) PGPROC *proc = &allProcs[pgprocno]; int nsubxids; + /* + * Filter by database OID if requested. + */ + if (OidIsValid(dbid) && proc->databaseId != dbid) + continue; + /* * Save subtransaction XIDs. Other backends can't add or remove * entries while we're holding XidGenLock. @@ -2791,6 +2811,7 @@ GetRunningTransactionData(void) * increases if slots do. */ + CurrentRunningXacts->dbid = dbid; CurrentRunningXacts->xcnt = count - subcount; CurrentRunningXacts->subxcnt = subcount; CurrentRunningXacts->subxid_status = suboverflowed ? SUBXIDS_IN_SUBTRANS : SUBXIDS_IN_ARRAY; diff --git a/src/backend/storage/ipc/standby.c b/src/backend/storage/ipc/standby.c index de9092fdf5b..c653ea742bc 100644 --- a/src/backend/storage/ipc/standby.c +++ b/src/backend/storage/ipc/standby.c @@ -1188,6 +1188,14 @@ standby_redo(XLogReaderState *record) xl_running_xacts *xlrec = (xl_running_xacts *) XLogRecGetData(record); RunningTransactionsData running; + /* + * Records issued for specific database are not suitable for physical + * replication because that affects the whole cluster. In particular, + * the list of XID is probably incomplete here. + */ + if (OidIsValid(xlrec->dbid)) + return; + running.xcnt = xlrec->xcnt; running.subxcnt = xlrec->subxcnt; running.subxid_status = xlrec->subxid_overflow ? SUBXIDS_MISSING : SUBXIDS_IN_ARRAY; @@ -1277,11 +1285,12 @@ standby_redo(XLogReaderState *record) * as there's no independent knob to just enable logical decoding. For * details of how this is used, check snapbuild.c's introductory comment. * + * If 'dbid' is valid, only gather transactions running in that database. * * Returns the RecPtr of the last inserted record. */ XLogRecPtr -LogStandbySnapshot(void) +LogStandbySnapshot(Oid dbid) { XLogRecPtr recptr; RunningTransactions running; @@ -1314,7 +1323,7 @@ LogStandbySnapshot(void) * Log details of all in-progress transactions. This should be the last * record we write, because standby will open up when it sees this. */ - running = GetRunningTransactionData(); + running = GetRunningTransactionData(dbid); /* * GetRunningTransactionData() acquired ProcArrayLock, we must release it. @@ -1358,6 +1367,7 @@ LogCurrentRunningXacts(RunningTransactions CurrRunningXacts) xl_running_xacts xlrec; XLogRecPtr recptr; + xlrec.dbid = CurrRunningXacts->dbid; xlrec.xcnt = CurrRunningXacts->xcnt; xlrec.subxcnt = CurrRunningXacts->subxcnt; xlrec.subxid_overflow = (CurrRunningXacts->subxid_status != SUBXIDS_IN_ARRAY); diff --git a/src/include/access/genam.h b/src/include/access/genam.h index b69320a7fc8..56c573399ab 100644 --- a/src/include/access/genam.h +++ b/src/include/access/genam.h @@ -136,6 +136,14 @@ typedef struct IndexOrderByDistance bool isnull; } IndexOrderByDistance; +/* + * Is the backend interested in shared catalogs when performing logical + * decoding? + * + * XXX Is there a better place for this declaration? + */ +extern bool accessSharedCatalogsInDecoding; + /* * generalized index_ interface routines (in indexam.c) */ diff --git a/src/include/access/xlog_internal.h b/src/include/access/xlog_internal.h index 755835d63bf..ae19982d88d 100644 --- a/src/include/access/xlog_internal.h +++ b/src/include/access/xlog_internal.h @@ -31,7 +31,7 @@ /* * Each page of XLOG file has a header like this: */ -#define XLOG_PAGE_MAGIC 0xD11E /* can be used as WAL version indicator */ +#define XLOG_PAGE_MAGIC 0xD11F /* can be used as WAL version indicator */ typedef struct XLogPageHeaderData { diff --git a/src/include/storage/procarray.h b/src/include/storage/procarray.h index abdf021e66e..377b3060b9f 100644 --- a/src/include/storage/procarray.h +++ b/src/include/storage/procarray.h @@ -49,7 +49,7 @@ extern bool ProcArrayInstallImportedXmin(TransactionId xmin, VirtualTransactionId *sourcevxid); extern bool ProcArrayInstallRestoredXmin(TransactionId xmin, PGPROC *proc); -extern RunningTransactions GetRunningTransactionData(void); +extern RunningTransactions GetRunningTransactionData(Oid dbid); extern bool TransactionIdIsInProgress(TransactionId xid); extern TransactionId GetOldestNonRemovableTransactionId(Relation rel); diff --git a/src/include/storage/standby.h b/src/include/storage/standby.h index 6a314c693cd..8715c08e94f 100644 --- a/src/include/storage/standby.h +++ b/src/include/storage/standby.h @@ -126,6 +126,7 @@ typedef enum typedef struct RunningTransactionsData { + Oid dbid; /* only track xacts in this database */ int xcnt; /* # of xact ids in xids[] */ int subxcnt; /* # of subxact ids in xids[] */ subxids_array_status subxid_status; @@ -143,7 +144,7 @@ typedef RunningTransactionsData *RunningTransactions; extern void LogAccessExclusiveLock(Oid dbOid, Oid relOid); extern void LogAccessExclusiveLockPrepare(void); -extern XLogRecPtr LogStandbySnapshot(void); +extern XLogRecPtr LogStandbySnapshot(Oid dbid); extern void LogStandbyInvalidations(int nmsgs, SharedInvalidationMessage *msgs, bool relcacheInitFileInval); diff --git a/src/include/storage/standbydefs.h b/src/include/storage/standbydefs.h index 231d251fd51..e75b7078766 100644 --- a/src/include/storage/standbydefs.h +++ b/src/include/storage/standbydefs.h @@ -46,6 +46,7 @@ typedef struct xl_standby_locks */ typedef struct xl_running_xacts { + Oid dbid; /* only track xacts in this database */ int xcnt; /* # of xact ids in xids[] */ int subxcnt; /* # of subxact ids in xids[] */ bool subxid_overflow; /* snapshot overflowed, subxids missing */ -- 2.47.3 --r2slln3zpmilwu22 Content-Type: text/x-diff; charset=utf-8 Content-Disposition: attachment; filename="v51-0009-Reserve-replication-slots-specifically-for-REPAC.patch" ^ permalink raw reply [nested|flat] 143+ 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; 143+ 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] 143+ 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; 143+ 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] 143+ 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; 143+ 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] 143+ 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; 143+ 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] 143+ 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; 143+ 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] 143+ 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; 143+ 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] 143+ 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; 143+ 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] 143+ 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; 143+ 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] 143+ 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; 143+ 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] 143+ 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; 143+ 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] 143+ 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; 143+ 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] 143+ 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; 143+ 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] 143+ 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; 143+ 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] 143+ 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; 143+ 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] 143+ 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; 143+ 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] 143+ 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; 143+ 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] 143+ 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; 143+ 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] 143+ 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; 143+ 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] 143+ 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; 143+ 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] 143+ 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; 143+ 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] 143+ 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; 143+ 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] 143+ 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; 143+ 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] 143+ 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; 143+ 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] 143+ 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; 143+ 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] 143+ 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; 143+ 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] 143+ 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; 143+ 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] 143+ 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; 143+ 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] 143+ 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; 143+ 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] 143+ 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; 143+ 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] 143+ 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; 143+ 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] 143+ 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; 143+ 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] 143+ 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; 143+ 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] 143+ 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; 143+ 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] 143+ 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; 143+ 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] 143+ 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; 143+ 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] 143+ 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; 143+ 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] 143+ 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; 143+ 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] 143+ 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; 143+ 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] 143+ 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; 143+ 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] 143+ 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; 143+ 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] 143+ 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; 143+ 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] 143+ 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; 143+ 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] 143+ 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; 143+ 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] 143+ 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; 143+ 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] 143+ 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; 143+ 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] 143+ 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; 143+ 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] 143+ 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; 143+ 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] 143+ 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; 143+ 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] 143+ 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; 143+ 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] 143+ 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; 143+ 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] 143+ 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; 143+ 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] 143+ 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; 143+ 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] 143+ 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; 143+ 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] 143+ 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; 143+ 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] 143+ 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; 143+ 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] 143+ 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; 143+ 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] 143+ 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; 143+ 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] 143+ 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; 143+ 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] 143+ 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; 143+ 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] 143+ 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; 143+ 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] 143+ 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; 143+ 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] 143+ 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; 143+ 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] 143+ 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; 143+ 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] 143+ 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; 143+ 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] 143+ 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; 143+ 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] 143+ 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; 143+ 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] 143+ 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; 143+ 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] 143+ 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; 143+ 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] 143+ 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; 143+ 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] 143+ 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; 143+ 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] 143+ 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; 143+ 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] 143+ 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; 143+ 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] 143+ 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; 143+ 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] 143+ 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; 143+ 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] 143+ 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; 143+ 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] 143+ 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; 143+ 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] 143+ 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; 143+ 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] 143+ 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; 143+ 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] 143+ 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; 143+ 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] 143+ 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; 143+ 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] 143+ 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; 143+ 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] 143+ 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; 143+ 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] 143+ 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; 143+ 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] 143+ 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; 143+ 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] 143+ 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; 143+ 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] 143+ 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; 143+ 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] 143+ 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; 143+ 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] 143+ 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; 143+ 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] 143+ 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; 143+ 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] 143+ 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; 143+ 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] 143+ 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; 143+ 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] 143+ 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; 143+ 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] 143+ 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; 143+ 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] 143+ 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; 143+ 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] 143+ 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; 143+ 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] 143+ 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; 143+ 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] 143+ 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; 143+ 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] 143+ 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; 143+ 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] 143+ 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; 143+ 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] 143+ 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; 143+ 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] 143+ 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; 143+ 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] 143+ 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; 143+ 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] 143+ 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; 143+ 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] 143+ 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; 143+ 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] 143+ 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; 143+ 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] 143+ 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; 143+ 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] 143+ 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; 143+ 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] 143+ 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; 143+ 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] 143+ 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; 143+ 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] 143+ 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; 143+ 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] 143+ 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; 143+ 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] 143+ 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; 143+ 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] 143+ 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; 143+ 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] 143+ 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; 143+ 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] 143+ 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; 143+ 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] 143+ 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; 143+ 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] 143+ 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; 143+ 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] 143+ 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; 143+ 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] 143+ 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; 143+ 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] 143+ 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; 143+ 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] 143+ 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; 143+ 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] 143+ 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; 143+ 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] 143+ 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; 143+ 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] 143+ 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; 143+ 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] 143+ 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; 143+ 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] 143+ messages in thread
end of thread, other threads:[~2026-05-12 10:27 UTC | newest] Thread overview: 143+ 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 v7 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 v8.1 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 v3 6/7] 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 v5 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 v8.1 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 v1 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 v7 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 5/6] Handle pg_get_expr default args in system_functions.sql Mark Wong <[email protected]> 2026-04-03 10:34 [PATCH v51 08/10] Introduce an option to make logical replication database specific. 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]>
This inbox is served by agora; see mirroring instructions for how to clone and mirror all data and code used for this inbox