From: Alexander Korotkov <akorotkov@postgresql.org>
To: pgsql-committers@lists.postgresql.org
Subject: pgsql: Fix WaitLSNWakeup() fast-path check for InvalidXLogRecPtr
Date: Sat, 15 Nov 2025 10:28:03 +0000
Message-ID: <E1vKDVj-006iAd-12@gemulon.postgresql.org> (raw)
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 <xunengzhou@gmail.com>
Reviewed-by: Alexander Korotkov <aekorotkov@gmail.com>
Branch
------
master
Details
-------
https://git.postgresql.org/pg/commitdiff/ede6acef49673df0a880edae405ca69393bb48d0
Modified Files
--------------
src/backend/access/transam/xlogwait.c | 8 ++++++--
1 file changed, 6 insertions(+), 2 deletions(-)
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To: pgsql-committers@postgresql.org
Cc: akorotkov@postgresql.org, pgsql-committers@lists.postgresql.org
Subject: Re: pgsql: Fix WaitLSNWakeup() fast-path check for InvalidXLogRecPtr
In-Reply-To: <E1vKDVj-006iAd-12@gemulon.postgresql.org>
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