From 69a925c3a04d8b3dcab109c3dcfbecabec96004e Mon Sep 17 00:00:00 2001 From: Maksim Melnikov Date: Thu, 10 Sep 2026 19:37:16 +0300 Subject: [PATCH] Fixing race between prepared transaction commit and checkpointer. --- src/backend/access/transam/twophase.c | 23 ++++++++++++----------- 1 file changed, 12 insertions(+), 11 deletions(-) diff --git a/src/backend/access/transam/twophase.c b/src/backend/access/transam/twophase.c index 48e478a4ecb..d6e52f6d814 100644 --- a/src/backend/access/transam/twophase.c +++ b/src/backend/access/transam/twophase.c @@ -561,15 +561,7 @@ LockGXact(const char *gid, Oid user) { int i; - /* on first call, register the exit hook */ - if (!twophaseExitRegistered) - { - before_shmem_exit(AtProcExit_Twophase, 0); - twophaseExitRegistered = true; - } - - LWLockAcquire(TwoPhaseStateLock, LW_EXCLUSIVE); - + Assert(LWLockHeldByMeInMode(TwoPhaseStateLock, LW_EXCLUSIVE)); for (i = 0; i < TwoPhaseState->numPrepXacts; i++) { GlobalTransaction gxact = TwoPhaseState->prepXacts[i]; @@ -610,11 +602,10 @@ LockGXact(const char *gid, Oid user) gxact->locking_backend = MyProcNumber; MyLockedGxact = gxact; - LWLockRelease(TwoPhaseStateLock); - return gxact; } + /* Release acquired lock before error, lock is held check placed on method header */ LWLockRelease(TwoPhaseStateLock); ereport(ERROR, @@ -1522,6 +1513,15 @@ FinishPreparedTransaction(const char *gid, bool isCommit) xl_xact_stats_item *abortstats; SharedInvalidationMessage *invalmsgs; + /* on first call, register the exit hook */ + if (!twophaseExitRegistered) + { + before_shmem_exit(AtProcExit_Twophase, 0); + twophaseExitRegistered = true; + } + + LWLockAcquire(TwoPhaseStateLock, LW_EXCLUSIVE); + /* * Validate the GID, and lock the GXACT to ensure that two backends do not * try to commit the same GID at once. @@ -1541,6 +1541,7 @@ FinishPreparedTransaction(const char *gid, bool isCommit) else XlogReadTwoPhaseData(gxact->prepare_start_lsn, &buf, NULL); + LWLockRelease(TwoPhaseStateLock); /* * Disassemble the header area -- 2.43.0