From ede6acef49673df0a880edae405ca69393bb48d0 Mon Sep 17 00:00:00 2001 From: Alexander Korotkov Date: Sat, 15 Nov 2025 12:16:23 +0200 Subject: [PATCH] Fix WaitLSNWakeup() fast-path check for InvalidXLogRecPtr WaitLSNWakeup() incorrectly returned early when called with InvalidXLogRecPtr (meaning "wake all waiters"), because the fast-path check compared minWaitedLSN > 0 without validating currentLSN first. This caused WAIT FOR LSN commands to wait indefinitely during standby promotion until random signals woke them. Add an XLogRecPtrIsValid() check before the comparison so that InvalidXLogRecPtr bypasses the fast-path and wakes all waiters immediately. Discussion: https://postgr.es/m/CABPTF7UieOYbOgH3EnQCasaqcT1T4N6V2wammwrWCohQTnD_Lw%40mail.gmail.com Author: Xuneng Zhou Reviewed-by: Alexander Korotkov --- src/backend/access/transam/xlogwait.c | 8 ++++++-- 1 file changed, 6 insertions(+), 2 deletions(-) diff --git a/src/backend/access/transam/xlogwait.c b/src/backend/access/transam/xlogwait.c index 34fa41ed9b2..78de93db47f 100644 --- a/src/backend/access/transam/xlogwait.c +++ b/src/backend/access/transam/xlogwait.c @@ -270,8 +270,12 @@ WaitLSNWakeup(WaitLSNType lsnType, XLogRecPtr currentLSN) Assert(i >= 0 && i < (int) WAIT_LSN_TYPE_COUNT); - /* Fast path check */ - if (pg_atomic_read_u64(&waitLSNState->minWaitedLSN[i]) > currentLSN) + /* + * Fast path check. Skip if currentLSN is InvalidXLogRecPtr, which means + * "wake all waiters" (e.g., during promotion when recovery ends). + */ + if (XLogRecPtrIsValid(currentLSN) && + pg_atomic_read_u64(&waitLSNState->minWaitedLSN[i]) > currentLSN) return; wakeupWaiters(lsnType, currentLSN);