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help / color / mirror / Atom feedFrom: Xuneng Zhou <[email protected]>
To: Alexander Korotkov <[email protected]>
Cc: Heikki Linnakangas <[email protected]>
Cc: Peter Eisentraut <[email protected]>
Cc: Andres Freund <[email protected]>
Cc: Thomas Munro <[email protected]>
Cc: Álvaro Herrera <[email protected]>
Cc: Chao Li <[email protected]>
Cc: pgsql-hackers <[email protected]>
Cc: Michael Paquier <[email protected]>
Cc: jian he <[email protected]>
Cc: Tomas Vondra <[email protected]>
Cc: Yura Sokolov <[email protected]>
Subject: Re: Implement waiting for wal lsn replay: reloaded
Date: Tue, 27 Jan 2026 09:14:43 +0800
Message-ID: <CABPTF7Wdq6KbvC3EhLX3Pz=ODCCPEX7qVQ+E=cokkB91an2E-A@mail.gmail.com> (raw)
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Hi Alexander,
Heikki spotted a misplaced wake-up call for replay waiters in
PerformWalRecovery. He suggested that the WaitLSNWakeup needs to be
invoked immediately after wal record is applied to avoid the potential
missed wake-ups when recovery stops/pauses/promotes. It makes sense to
me. Please check the attached patch to fix that.
--
Best,
Xuneng
Attachments:
[application/octet-stream] v1-0001-Wake-LSN-waiters-before-recovery-target-stop.patch (1.6K, 2-v1-0001-Wake-LSN-waiters-before-recovery-target-stop.patch)
download | inline diff:
From 3e692c636838a928918266174c3e139274384702 Mon Sep 17 00:00:00 2001
From: alterego655 <[email protected]>
Date: Tue, 27 Jan 2026 09:00:39 +0800
Subject: [PATCH v1] Wake LSN waiters before recovery target stop
Move WaitLSNWakeup() immediately after ApplyWalRecord() so waiters are
signaled even when recoveryStopsAfter() breaks out for pause/promotion
targets.
---
src/backend/access/transam/xlogrecovery.c | 14 +++++++-------
1 file changed, 7 insertions(+), 7 deletions(-)
diff --git a/src/backend/access/transam/xlogrecovery.c b/src/backend/access/transam/xlogrecovery.c
index b9393e551b7..36daa3d8587 100644
--- a/src/backend/access/transam/xlogrecovery.c
+++ b/src/backend/access/transam/xlogrecovery.c
@@ -1777,13 +1777,6 @@ PerformWalRecovery(void)
*/
ApplyWalRecord(xlogreader, record, &replayTLI);
- /* Exit loop if we reached inclusive recovery target */
- if (recoveryStopsAfter(xlogreader))
- {
- reachedRecoveryTarget = true;
- break;
- }
-
/*
* If we replayed an LSN that someone was waiting for then walk
* over the shared memory array and set latches to notify the
@@ -1794,6 +1787,13 @@ PerformWalRecovery(void)
pg_atomic_read_u64(&waitLSNState->minWaitedLSN[WAIT_LSN_TYPE_STANDBY_REPLAY])))
WaitLSNWakeup(WAIT_LSN_TYPE_STANDBY_REPLAY, XLogRecoveryCtl->lastReplayedEndRecPtr);
+ /* Exit loop if we reached inclusive recovery target */
+ if (recoveryStopsAfter(xlogreader))
+ {
+ reachedRecoveryTarget = true;
+ break;
+ }
+
/* Else, try to fetch the next WAL record */
record = ReadRecord(xlogprefetcher, LOG, false, replayTLI);
} while (record != NULL);
--
2.51.0
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Subject: Re: Implement waiting for wal lsn replay: reloaded
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