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[PATCH v1 1/2] Report wait event for cost-based vacuum delay 195+ messages / 4 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; 195+ 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] 195+ messages in thread
* [PATCH v2] Avoid orphaned objects dependencies @ 2024-03-29 15:43 Bertrand Drouvot <[email protected]> 0 siblings, 0 replies; 195+ messages in thread From: Bertrand Drouvot @ 2024-03-29 15:43 UTC (permalink / raw) It's currently possible to create orphaned objects dependencies, for example: Scenario 1: session 1: begin; drop schema schem; session 2: create a function in the schema schem session 1: commit; With the above, the function created in session 2 would be linked to a non existing schema. Scenario 2: session 1: begin; create a function in the schema schem session 2: drop schema schem; session 1: commit; With the above, the function created in session 1 would be linked to a non existing schema. To avoid those scenarios, a new lock (that conflicts with a lock taken by DROP) has been put in place when the dependencies are being recorded. With this in place, the drop schema in scenario 2 would be locked. Also, after locking the object, the patch checks that the object still exists: with this in place session 2 in scenario 1 would be locked and would report an error once session 1 committs (that would not be the case should session 1 abort the transaction). The patch adds a few tests for some dependency cases (that would currently produce orphaned objects): - schema and function (as the above scenarios) - function and type - table and type --- src/backend/catalog/dependency.c | 48 +++++++++++++ src/backend/catalog/objectaddress.c | 70 +++++++++++++++++++ src/backend/catalog/pg_depend.c | 6 ++ src/include/catalog/dependency.h | 1 + src/include/catalog/objectaddress.h | 1 + src/test/modules/Makefile | 1 + src/test/modules/meson.build | 1 + .../test_dependencies_locks/.gitignore | 3 + .../modules/test_dependencies_locks/Makefile | 14 ++++ .../expected/test_dependencies_locks.out | 49 +++++++++++++ .../test_dependencies_locks/meson.build | 12 ++++ .../specs/test_dependencies_locks.spec | 39 +++++++++++ 12 files changed, 245 insertions(+) 38.1% src/backend/catalog/ 30.7% src/test/modules/test_dependencies_locks/expected/ 19.5% src/test/modules/test_dependencies_locks/specs/ 8.7% src/test/modules/test_dependencies_locks/ diff --git a/src/backend/catalog/dependency.c b/src/backend/catalog/dependency.c index d4b5b2ade1..e3b66025dd 100644 --- a/src/backend/catalog/dependency.c +++ b/src/backend/catalog/dependency.c @@ -1517,6 +1517,54 @@ AcquireDeletionLock(const ObjectAddress *object, int flags) } } +/* + * depLockAndCheckObject + * + * Lock the object that we are about to record a dependency on. + * After it's locked, verify that it hasn't been dropped while we + * weren't looking. If the object has been dropped, this function + * does not return! + */ +void +depLockAndCheckObject(const ObjectAddress *object) +{ + char *object_description; + + /* + * Those don't rely on LockDatabaseObject() when being dropped (see + * AcquireDeletionLock()). Also it looks like they can not produce + * orphaned dependent objects when being dropped. + */ + if (object->classId == RelationRelationId || object->classId == AuthMemRelationId) + return; + + object_description = getObjectDescription(object, true); + + /* assume we should lock the whole object not a sub-object */ + LockDatabaseObject(object->classId, object->objectId, 0, AccessShareLock); + + /* check if object still exists */ + if (!ObjectByIdExist(object, false)) + { + /* + * It might be possible that we are creating it, so bypass the syscache + * lookup and use a dirty snaphot instead. + */ + if (!ObjectByIdExist(object, true)) + { + if(object_description) + ereport(ERROR, errmsg("%s does not exist", object_description)); + else + ereport(ERROR, errmsg("a dependent object does not exist")); + } + } + + if (object_description) + pfree(object_description); + + return; +} + /* * ReleaseDeletionLock - release an object deletion lock * diff --git a/src/backend/catalog/objectaddress.c b/src/backend/catalog/objectaddress.c index 7b536ac6fd..c2b873dd81 100644 --- a/src/backend/catalog/objectaddress.c +++ b/src/backend/catalog/objectaddress.c @@ -2590,6 +2590,76 @@ get_object_namespace(const ObjectAddress *address) return oid; } +/* + * ObjectByIdExist + * + * Return whether the given object exists. + * + * Works for most catalogs, if no special processing is needed. + */ +bool +ObjectByIdExist(const ObjectAddress *address, bool use_dirty_snapshot) +{ + HeapTuple tuple; + int cache = -1; + const ObjectPropertyType *property; + + if (!use_dirty_snapshot) + { + property = get_object_property_data(address->classId); + + cache = property->oid_catcache_id; + } + + if (cache >= 0) + { + /* Fetch tuple from syscache. */ + tuple = SearchSysCache1(cache, ObjectIdGetDatum(address->objectId)); + + if (!HeapTupleIsValid(tuple)) + { + return false; + } + + ReleaseSysCache(tuple); + + return true; + } + else + { + Relation rel; + ScanKeyData skey[1]; + SysScanDesc scan; + SnapshotData DirtySnapshot; + Snapshot snapshot; + + if (use_dirty_snapshot) + { + InitDirtySnapshot(DirtySnapshot); + snapshot = &DirtySnapshot; + } + else + snapshot = NULL; + + rel = table_open(address->classId, AccessShareLock); + + ScanKeyInit(&skey[0], + get_object_attnum_oid(address->classId), + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(address->objectId)); + + scan = systable_beginscan(rel, get_object_oid_index(address->classId), true, + snapshot, 1, skey); + + /* we expect exactly one match */ + tuple = systable_getnext(scan); + systable_endscan(scan); + table_close(rel, AccessShareLock); + + return (HeapTupleIsValid(tuple)); + } +} + /* * Return ObjectType for the given object type as given by * getObjectTypeDescription; if no valid ObjectType code exists, but it's a diff --git a/src/backend/catalog/pg_depend.c b/src/backend/catalog/pg_depend.c index f85a898de8..6bb218f5dd 100644 --- a/src/backend/catalog/pg_depend.c +++ b/src/backend/catalog/pg_depend.c @@ -106,6 +106,12 @@ recordMultipleDependencies(const ObjectAddress *depender, if (isObjectPinned(referenced)) continue; + /* + * Acquire a lock and check object still exists while recording the + * dependency. XXX - Should we do so only for DEPENDENCY_NORMAL? + */ + depLockAndCheckObject(referenced); + if (slot_init_count < max_slots) { slot[slot_stored_count] = MakeSingleTupleTableSlot(RelationGetDescr(dependDesc), diff --git a/src/include/catalog/dependency.h b/src/include/catalog/dependency.h index ec654010d4..8915548711 100644 --- a/src/include/catalog/dependency.h +++ b/src/include/catalog/dependency.h @@ -94,6 +94,7 @@ typedef struct ObjectAddresses ObjectAddresses; /* in dependency.c */ extern void AcquireDeletionLock(const ObjectAddress *object, int flags); +extern void depLockAndCheckObject(const ObjectAddress *object); extern void ReleaseDeletionLock(const ObjectAddress *object); diff --git a/src/include/catalog/objectaddress.h b/src/include/catalog/objectaddress.h index 3a70d80e32..04891abcc1 100644 --- a/src/include/catalog/objectaddress.h +++ b/src/include/catalog/objectaddress.h @@ -53,6 +53,7 @@ extern void check_object_ownership(Oid roleid, Node *object, Relation relation); extern Oid get_object_namespace(const ObjectAddress *address); +extern bool ObjectByIdExist(const ObjectAddress *address, bool use_dirty_snapshot); extern bool is_objectclass_supported(Oid class_id); extern const char *get_object_class_descr(Oid class_id); diff --git a/src/test/modules/Makefile b/src/test/modules/Makefile index 256799f520..75f357100f 100644 --- a/src/test/modules/Makefile +++ b/src/test/modules/Makefile @@ -17,6 +17,7 @@ SUBDIRS = \ test_copy_callbacks \ test_custom_rmgrs \ test_ddl_deparse \ + test_dependencies_locks \ test_dsa \ test_dsm_registry \ test_extensions \ diff --git a/src/test/modules/meson.build b/src/test/modules/meson.build index d8fe059d23..60305dcccd 100644 --- a/src/test/modules/meson.build +++ b/src/test/modules/meson.build @@ -16,6 +16,7 @@ subdir('test_bloomfilter') subdir('test_copy_callbacks') subdir('test_custom_rmgrs') subdir('test_ddl_deparse') +subdir('test_dependencies_locks') subdir('test_dsa') subdir('test_dsm_registry') subdir('test_extensions') diff --git a/src/test/modules/test_dependencies_locks/.gitignore b/src/test/modules/test_dependencies_locks/.gitignore new file mode 100644 index 0000000000..bf000faac4 --- /dev/null +++ b/src/test/modules/test_dependencies_locks/.gitignore @@ -0,0 +1,3 @@ +# Generated subdirectories +/log/ +/output_iso diff --git a/src/test/modules/test_dependencies_locks/Makefile b/src/test/modules/test_dependencies_locks/Makefile new file mode 100644 index 0000000000..7491048380 --- /dev/null +++ b/src/test/modules/test_dependencies_locks/Makefile @@ -0,0 +1,14 @@ +# src/test/modules/test_dependencies_locks/Makefile + +ISOLATION = test_dependencies_locks + +ifdef USE_PGXS +PG_CONFIG = pg_config +PGXS := $(shell $(PG_CONFIG) --pgxs) +include $(PGXS) +else +subdir = src/test/modules/test_dependencies_locks +top_builddir = ../../../.. +include $(top_builddir)/src/Makefile.global +include $(top_srcdir)/contrib/contrib-global.mk +endif diff --git a/src/test/modules/test_dependencies_locks/expected/test_dependencies_locks.out b/src/test/modules/test_dependencies_locks/expected/test_dependencies_locks.out new file mode 100644 index 0000000000..d0980f77d5 --- /dev/null +++ b/src/test/modules/test_dependencies_locks/expected/test_dependencies_locks.out @@ -0,0 +1,49 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_begin s1_create_function_in_schema s2_drop_schema s1_commit +step s1_begin: BEGIN; +step s1_create_function_in_schema: CREATE FUNCTION testschema.foo() RETURNS int AS 'select 1' LANGUAGE sql; +step s2_drop_schema: DROP SCHEMA testschema; <waiting ...> +step s1_commit: COMMIT; +step s2_drop_schema: <... completed> +ERROR: cannot drop schema testschema because other objects depend on it + +starting permutation: s2_begin s2_drop_schema s1_create_function_in_schema s2_commit +step s2_begin: BEGIN; +step s2_drop_schema: DROP SCHEMA testschema; +step s1_create_function_in_schema: CREATE FUNCTION testschema.foo() RETURNS int AS 'select 1' LANGUAGE sql; <waiting ...> +step s2_commit: COMMIT; +step s1_create_function_in_schema: <... completed> +ERROR: schema testschema does not exist + +starting permutation: s1_begin s1_create_function_with_type s2_drop_foo_type s1_commit +step s1_begin: BEGIN; +step s1_create_function_with_type: CREATE FUNCTION footype(num foo) RETURNS int AS 'select 1' LANGUAGE sql; +step s2_drop_foo_type: DROP TYPE public.foo; <waiting ...> +step s1_commit: COMMIT; +step s2_drop_foo_type: <... completed> +ERROR: cannot drop type foo because other objects depend on it + +starting permutation: s2_begin s2_drop_foo_type s1_create_function_with_type s2_commit +step s2_begin: BEGIN; +step s2_drop_foo_type: DROP TYPE public.foo; +step s1_create_function_with_type: CREATE FUNCTION footype(num foo) RETURNS int AS 'select 1' LANGUAGE sql; <waiting ...> +step s2_commit: COMMIT; +step s1_create_function_with_type: <... completed> +ERROR: type foo does not exist + +starting permutation: s1_begin s1_create_table_with_type s2_drop_footab_type s1_commit +step s1_begin: BEGIN; +step s1_create_table_with_type: CREATE TABLE tabtype(a footab); +step s2_drop_footab_type: DROP TYPE public.footab; <waiting ...> +step s1_commit: COMMIT; +step s2_drop_footab_type: <... completed> +ERROR: cannot drop type footab because other objects depend on it + +starting permutation: s2_begin s2_drop_footab_type s1_create_table_with_type s2_commit +step s2_begin: BEGIN; +step s2_drop_footab_type: DROP TYPE public.footab; +step s1_create_table_with_type: CREATE TABLE tabtype(a footab); <waiting ...> +step s2_commit: COMMIT; +step s1_create_table_with_type: <... completed> +ERROR: type footab does not exist diff --git a/src/test/modules/test_dependencies_locks/meson.build b/src/test/modules/test_dependencies_locks/meson.build new file mode 100644 index 0000000000..92a978ab93 --- /dev/null +++ b/src/test/modules/test_dependencies_locks/meson.build @@ -0,0 +1,12 @@ +# Copyright (c) 2024, PostgreSQL Global Development Group + +tests += { + 'name': 'test_dependencies_locks', + 'sd': meson.current_source_dir(), + 'bd': meson.current_build_dir(), + 'isolation': { + 'specs': [ + 'test_dependencies_locks', + ], + }, +} diff --git a/src/test/modules/test_dependencies_locks/specs/test_dependencies_locks.spec b/src/test/modules/test_dependencies_locks/specs/test_dependencies_locks.spec new file mode 100644 index 0000000000..fd15bd2a78 --- /dev/null +++ b/src/test/modules/test_dependencies_locks/specs/test_dependencies_locks.spec @@ -0,0 +1,39 @@ +setup +{ + CREATE SCHEMA testschema; + CREATE TYPE public.foo as enum ('one', 'two'); + CREATE TYPE public.footab as enum ('three', 'four'); +} + +teardown +{ + DROP FUNCTION IF EXISTS testschema.foo(); + DROP FUNCTION IF EXISTS footype(num foo); + DROP TABLE IF EXISTS tabtype; + DROP SCHEMA IF EXISTS testschema; + DROP TYPE IF EXISTS public.foo; + DROP TYPE IF EXISTS public.footab; +} + +session "s1" + +step "s1_begin" { BEGIN; } +step "s1_create_function_in_schema" { CREATE FUNCTION testschema.foo() RETURNS int AS 'select 1' LANGUAGE sql; } +step "s1_create_function_with_type" { CREATE FUNCTION footype(num foo) RETURNS int AS 'select 1' LANGUAGE sql; } +step "s1_create_table_with_type" { CREATE TABLE tabtype(a footab); } +step "s1_commit" { COMMIT; } + +session "s2" + +step "s2_begin" { BEGIN; } +step "s2_drop_schema" { DROP SCHEMA testschema; } +step "s2_drop_foo_type" { DROP TYPE public.foo; } +step "s2_drop_footab_type" { DROP TYPE public.footab; } +step "s2_commit" { COMMIT; } + +permutation "s1_begin" "s1_create_function_in_schema" "s2_drop_schema" "s1_commit" +permutation "s2_begin" "s2_drop_schema" "s1_create_function_in_schema" "s2_commit" +permutation "s1_begin" "s1_create_function_with_type" "s2_drop_foo_type" "s1_commit" +permutation "s2_begin" "s2_drop_foo_type" "s1_create_function_with_type" "s2_commit" +permutation "s1_begin" "s1_create_table_with_type" "s2_drop_footab_type" "s1_commit" +permutation "s2_begin" "s2_drop_footab_type" "s1_create_table_with_type" "s2_commit" -- 2.34.1 --Nnmp7Q5BciyL9zub-- ^ permalink raw reply [nested|flat] 195+ 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; 195+ 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] 195+ 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; 195+ 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] 195+ 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; 195+ 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] 195+ 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; 195+ 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] 195+ 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; 195+ 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] 195+ 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; 195+ 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] 195+ 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; 195+ 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] 195+ 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; 195+ 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] 195+ 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; 195+ 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] 195+ 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; 195+ 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] 195+ 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; 195+ 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] 195+ 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; 195+ 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] 195+ 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; 195+ 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] 195+ 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; 195+ 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] 195+ 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; 195+ 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] 195+ 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; 195+ 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] 195+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 195+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 195+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 195+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 195+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 195+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 195+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 195+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 195+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 195+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 195+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 195+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 195+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 195+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 195+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 195+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 195+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 195+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 195+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 195+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 195+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 195+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 195+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 195+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 195+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 195+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 195+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 195+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 195+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 195+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 195+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 195+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 195+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 195+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 195+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 195+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 195+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 195+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 195+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 195+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 195+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 195+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 195+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 195+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 195+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 195+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 195+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 195+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 195+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 195+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 195+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 195+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 195+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 195+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 195+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 195+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 195+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 195+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 195+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 195+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 195+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 195+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 195+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 195+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 195+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 195+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 195+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 195+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 195+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 195+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 195+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 195+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 195+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 195+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 195+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 195+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 195+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 195+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 195+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 195+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 195+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 195+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 195+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 195+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 195+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 195+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 195+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 195+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 195+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 195+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 195+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 195+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 195+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 195+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 195+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 195+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 195+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 195+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 195+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 195+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 195+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 195+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 195+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 195+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 195+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 195+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 195+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 195+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 195+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 195+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 195+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 195+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 195+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 195+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 195+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 195+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 195+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 195+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 195+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 195+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 195+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 195+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 195+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 195+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 195+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 195+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 195+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 195+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 195+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 195+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 195+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 195+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 195+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 195+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 195+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 195+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 195+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 195+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 195+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 195+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 195+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 195+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 195+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 195+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 195+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 195+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 195+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 195+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 195+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 195+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 195+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 195+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 195+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 195+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 195+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 195+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 195+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 195+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 195+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 195+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 195+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 195+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 195+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 195+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 195+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 195+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 195+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 195+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 195+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 195+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 195+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 195+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 195+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 195+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 195+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 195+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 195+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 195+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 195+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 195+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 195+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 195+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 195+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 195+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 195+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 195+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 195+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 195+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 195+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 195+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 195+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 195+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 195+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 195+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 195+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 195+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 195+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 195+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 195+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 195+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 195+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 195+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 195+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 195+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 195+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 195+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 195+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 195+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 195+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 195+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 195+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 195+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 195+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 195+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 195+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 195+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 195+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 195+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 195+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 195+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 195+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 195+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 195+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 195+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 195+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 195+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 195+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 195+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 195+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 195+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 195+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 195+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 195+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 195+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 195+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 195+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 195+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 195+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 195+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 195+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 195+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 195+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 195+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 195+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 195+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 195+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 195+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 195+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 195+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 195+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 195+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 195+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 195+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 195+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 195+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 195+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 195+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 195+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 195+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 195+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 195+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 195+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 195+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 195+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 195+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 195+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 195+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 195+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 195+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 195+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 195+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 195+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 195+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 195+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 195+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 195+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 195+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 195+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 195+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 195+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 195+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 195+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 195+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 195+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 195+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 195+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 195+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 195+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 195+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 195+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 195+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 195+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 195+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 195+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 195+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 195+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 195+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 195+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 195+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 195+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 195+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 195+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 195+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 195+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 195+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 195+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 195+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 195+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 195+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 195+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 195+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 195+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 195+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 195+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 195+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 195+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 195+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 195+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 195+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 195+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 195+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 195+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 195+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 195+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 195+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 195+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 195+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 195+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 195+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 195+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 195+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 195+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 195+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 195+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 195+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 195+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 195+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 195+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 195+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 195+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 195+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 195+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 195+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 195+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 195+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 195+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 195+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 195+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 195+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 195+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 195+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 195+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 195+ messages in thread
* [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. @ 2026-05-12 10:27 Antonin Houska <[email protected]> 0 siblings, 0 replies; 195+ messages in thread From: Antonin Houska @ 2026-05-12 10:27 UTC (permalink / raw) The fix: https://www.postgresql.org/message-id/77611.1778055944%40localhost --- src/backend/access/transam/xact.c | 2 + src/backend/commands/repack_worker.c | 2 + src/test/isolation/isolationtester.c | 9 +- .../expected/repack_running_xacts.out | 81 ++++++++++++ .../specs/repack_running_xacts.spec | 119 ++++++++++++++++++ 5 files changed, 212 insertions(+), 1 deletion(-) create mode 100644 src/test/modules/injection_points/expected/repack_running_xacts.out create mode 100644 src/test/modules/injection_points/specs/repack_running_xacts.spec diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 5586fbe5b07..b63ee166028 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -65,6 +65,7 @@ #include "utils/builtins.h" #include "utils/combocid.h" #include "utils/guc.h" +#include "utils/injection_point.h" #include "utils/inval.h" #include "utils/memutils.h" #include "utils/relmapper.h" @@ -2428,6 +2429,7 @@ CommitTransaction(void) * must be done _before_ releasing locks we hold and _after_ * RecordTransactionCommit. */ + INJECTION_POINT("before-end-transaction", NULL); ProcArrayEndTransaction(MyProc, latestXid); /* diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c index c40f8c98e06..6835626d677 100644 --- a/src/backend/commands/repack_worker.c +++ b/src/backend/commands/repack_worker.c @@ -26,6 +26,7 @@ #include "storage/ipc.h" #include "storage/proc.h" #include "tcop/tcopprot.h" +#include "utils/injection_point.h" #include "utils/memutils.h" #define REPL_PLUGIN_NAME "pgrepack" @@ -233,6 +234,7 @@ repack_setup_logical_decoding(Oid relid) * Neither prepare_write nor do_write callback nor update_progress is * useful for us. */ + INJECTION_POINT("before-create-decoding-context", NULL); ctx = CreateInitDecodingContext(REPL_PLUGIN_NAME, NIL, true, diff --git a/src/test/isolation/isolationtester.c b/src/test/isolation/isolationtester.c index 440c875b8ac..8f17ee412c9 100644 --- a/src/test/isolation/isolationtester.c +++ b/src/test/isolation/isolationtester.c @@ -216,15 +216,22 @@ main(int argc, char **argv) * exactly expect concurrent use of test tables. However, autovacuum will * occasionally take AccessExclusiveLock to truncate a table, and we must * ignore that transient wait. + * + * If the session's backend is blocked, and if its background worker is + * waiting on an injection point, we assume that the injection point is + * the reason for the backend to be blocked. That's what we check in the + * second query of the UNION. XXX Should we use a separate query for that? */ initPQExpBuffer(&wait_query); appendPQExpBufferStr(&wait_query, + "WITH blocking(res) AS (" "SELECT pg_catalog.pg_isolation_test_session_is_blocked($1, '{"); /* The spec syntax requires at least one session; assume that here. */ appendPQExpBufferStr(&wait_query, conns[1].backend_pid_str); for (i = 2; i < nconns; i++) appendPQExpBuffer(&wait_query, ",%s", conns[i].backend_pid_str); - appendPQExpBufferStr(&wait_query, "}')"); + appendPQExpBufferStr(&wait_query, "}') UNION " + "SELECT pg_catalog.pg_isolation_test_session_is_blocked(pid, '{}') FROM pg_stat_activity WHERE leader_pid=$1) SELECT bool_or(res) FROM blocking"); res = PQprepare(conns[0].conn, PREP_WAITING, wait_query.data, 0, NULL); if (PQresultStatus(res) != PGRES_COMMAND_OK) diff --git a/src/test/modules/injection_points/expected/repack_running_xacts.out b/src/test/modules/injection_points/expected/repack_running_xacts.out new file mode 100644 index 00000000000..271fe2b97cb --- /dev/null +++ b/src/test/modules/injection_points/expected/repack_running_xacts.out @@ -0,0 +1,81 @@ +Parsed test spec with 5 sessions + +starting permutation: repack s3_assign_xid wakeup_bcdc s4_changes s4_attach s4_commit s3_commit s5_assign_xid wakeup_bet s5_commit check +injection_points_attach +----------------------- + +(1 row) + +step repack: + REPACK (CONCURRENTLY) repack_test; + <waiting ...> +step s3_assign_xid: + BEGIN; + INSERT INTO aux VALUES (1); + +step wakeup_bcdc: + SELECT injection_points_wakeup('before-create-decoding-context'); + +injection_points_wakeup +----------------------- + +(1 row) + +step s4_changes: + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); + +step s4_attach: + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); + +injection_points_set_local +-------------------------- + +(1 row) + +injection_points_attach +----------------------- + +(1 row) + +step s4_commit: + COMMIT; + <waiting ...> +step s3_commit: + COMMIT; + +step s5_assign_xid: + BEGIN; + INSERT INTO aux VALUES (2); + +step wakeup_bet: + SELECT injection_points_wakeup('before-end-transaction'); + +injection_points_wakeup +----------------------- + +(1 row) + +step repack: <... completed> +step s4_commit: <... completed> +step s5_commit: + COMMIT; + +step check: + TABLE repack_test; + +i|j +-+- +(0 rows) + +injection_points_detach +----------------------- + +(1 row) + +injection_points_detach +----------------------- + +(1 row) + diff --git a/src/test/modules/injection_points/specs/repack_running_xacts.spec b/src/test/modules/injection_points/specs/repack_running_xacts.spec new file mode 100644 index 00000000000..1f878514046 --- /dev/null +++ b/src/test/modules/injection_points/specs/repack_running_xacts.spec @@ -0,0 +1,119 @@ +setup +{ + CREATE EXTENSION injection_points; + CREATE TABLE repack_test(i int PRIMARY KEY, j int); + CREATE TABLE aux(i int); +} + +teardown +{ + DROP TABLE repack_test; + DROP TABLE aux; + DROP EXTENSION injection_points; +} + +session s1 +setup +{ + SELECT injection_points_attach('before-create-decoding-context', 'wait'); +} +step repack +{ + REPACK (CONCURRENTLY) repack_test; +} +step check +{ + TABLE repack_test; +} +teardown +{ + SELECT injection_points_detach('before-create-decoding-context'); +} + +session s2 +step wakeup_bcdc +{ + SELECT injection_points_wakeup('before-create-decoding-context'); +} +step wakeup_bet +{ + SELECT injection_points_wakeup('before-end-transaction'); +} + +session s3 +step s3_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (1); +} +step s3_commit +{ + COMMIT; +} + +session s4 +step s4_changes +{ + BEGIN; + INSERT INTO repack_test(i, j) VALUES (1, 1); +} +# Do not attach in the setup section, that would be too soon. +step s4_attach +{ + SELECT injection_points_set_local(); + SELECT injection_points_attach('before-end-transaction', 'wait'); +} +step s4_commit +{ + COMMIT; +} +teardown +{ + SELECT injection_points_detach('before-end-transaction'); +} + +session s5 +step s5_assign_xid +{ + BEGIN; + INSERT INTO aux VALUES (2); +} +step s5_commit +{ + COMMIT; +} + +permutation +repack +# Assign XID so that a running transaction prevents the snapshot builder from +# reaching CONSISTENT state immediately. It will wait for this to complete +# after having reached BUILDING_SNAPSHOT. +s3_assign_xid +# Let the decoding setup start. +wakeup_bcdc +# Likewise, the snapshot builder will wait for the s4's xact to complete after +# having reached FULL_SNAPSHOT. This is the problematic transaction, so let it +# do some changes. +s4_changes +# Attach to the 'before-end-transaction' injection point that s4 will need +# during commit. +s4_attach +# Only write commit record for s4, but do not remove the xact from procarray +# yet. Thus the snapshot builder still needs to wait. +s4_commit +# Let the snapshot builder proceed to FULL_SNAPSHOT. +s3_commit +# Start another transaction so that CONSISTENT is not reached "directly", +# i.e. due to no running transaction. It's important here that builder->xmin +# does not advance. +s5_assign_xid +# Remove s4 xact from procarray, and thus reach the CONSISTENT state. Since +# the COMMIT appeared in WAL too early (i.e. when the snapshot builder state +# did not allow decoding of COMMIT records yet), the snapshot builder will +# consider s4 running. This is also due to returning from +# SnapBuildProcessRunningXacts() too early, w/o advancing builder->xmin. +wakeup_bet +# s5 is not needed anymore +s5_commit +# Show that the data changes performed by s4 are lost. +check -- 2.47.3 --=-=-=-- ^ permalink raw reply [nested|flat] 195+ messages in thread
end of thread, other threads:[~2026-05-12 10:27 UTC | newest] Thread overview: 195+ 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]> 2024-03-29 15:43 [PATCH v2] Avoid orphaned objects dependencies Bertrand Drouvot <[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 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 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 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 v1 5/6] Handle pg_get_expr default args in system_functions.sql Mark Wong <[email protected]> 2025-12-09 19:17 [PATCH v5 5/6] Handle pg_get_expr default args in system_functions.sql Mark Wong <[email protected]> 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 v8 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 v4 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 5/6] Handle pg_get_expr default args in system_functions.sql Mark Wong <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]> 2026-05-12 10:27 [PATCH] Test to demonstrate bug in commit 0d3dba38c7 and to verify a fix. Antonin Houska <[email protected]>
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