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pgsql: Wake primary_flush waiters after implicit WAL flushes 2+ messages / 1 participants [nested] [flat]
* pgsql: Wake primary_flush waiters after implicit WAL flushes @ 2026-09-12 20:30 Alexander Korotkov <akorotkov@postgresql.org> 0 siblings, 0 replies; 2+ messages in thread From: Alexander Korotkov @ 2026-09-12 20:30 UTC (permalink / raw) To: pgsql-committers@lists.postgresql.org Wake primary_flush waiters after implicit WAL flushes XLogWrite() can advance the flush position when it finishes a WAL segment, even if its caller requested only a write. When this happens while AdvanceXLInsertBuffer() recycles a buffer, primary_flush waiters are not notified and can sleep until an unrelated flush or checkpoint. Track such progress with a process-local pending flag and perform the wakeup after releasing WAL write and insertion locks, keeping WaitLSNLock acquisition outside the contended WAL path. Add a deterministic injection-point test that forces this path and inspects the registration directly in shared memory. Author: Xuneng Zhou <xunengzhou@gmail.com> Discussion: https://postgr.es/m/CABPTF7U0gW5%2B-4oL7-qdML-yerZxUb7ku4QXp7JxCYo0qyJ_Tw%40mail.gmail.com Reviewed-by: Alexander Korotkov <aekorotkov@gmail.com> Backpatch-through: 19 Branch ------ master Details ------- https://git.postgresql.org/pg/commitdiff/d61f9c90f2ef96b38eceb592b63c688d74cf7611 Modified Files -------------- src/backend/access/transam/xlog.c | 34 ++++++++ src/backend/access/transam/xlogwait.c | 3 + src/backend/postmaster/walwriter.c | 3 + src/test/recovery/t/049_wait_for_lsn.pl | 146 ++++++++++++++++++++++++++++++++ 4 files changed, 186 insertions(+) ^ permalink raw reply [nested|flat] 2+ messages in thread
* pgsql: Wake primary_flush waiters after implicit WAL flushes @ 2026-09-12 20:30 Alexander Korotkov <akorotkov@postgresql.org> 0 siblings, 0 replies; 2+ messages in thread From: Alexander Korotkov @ 2026-09-12 20:30 UTC (permalink / raw) To: pgsql-committers@lists.postgresql.org Wake primary_flush waiters after implicit WAL flushes XLogWrite() can advance the flush position when it finishes a WAL segment, even if its caller requested only a write. When this happens while AdvanceXLInsertBuffer() recycles a buffer, primary_flush waiters are not notified and can sleep until an unrelated flush or checkpoint. Track such progress with a process-local pending flag and perform the wakeup after releasing WAL write and insertion locks, keeping WaitLSNLock acquisition outside the contended WAL path. Add a deterministic injection-point test that forces this path and inspects the registration directly in shared memory. Author: Xuneng Zhou <xunengzhou@gmail.com> Discussion: https://postgr.es/m/CABPTF7U0gW5%2B-4oL7-qdML-yerZxUb7ku4QXp7JxCYo0qyJ_Tw%40mail.gmail.com Reviewed-by: Alexander Korotkov <aekorotkov@gmail.com> Backpatch-through: 19 Branch ------ REL_19_STABLE Details ------- https://git.postgresql.org/pg/commitdiff/854be98cc4aad48a960197e4d70b1da9063a906e Modified Files -------------- src/backend/access/transam/xlog.c | 34 ++++++++ src/backend/access/transam/xlogwait.c | 3 + src/backend/postmaster/walwriter.c | 3 + src/test/recovery/t/049_wait_for_lsn.pl | 146 ++++++++++++++++++++++++++++++++ 4 files changed, 186 insertions(+) ^ permalink raw reply [nested|flat] 2+ messages in thread
end of thread, other threads:[~2026-09-12 20:30 UTC | newest] Thread overview: 2+ messages (download: mbox mbox.gz follow: Atom feed) -- links below jump to the message on this page -- 2026-09-12 20:30 pgsql: Wake primary_flush waiters after implicit WAL flushes Alexander Korotkov <akorotkov@postgresql.org> 2026-09-12 20:30 pgsql: Wake primary_flush waiters after implicit WAL flushes Alexander Korotkov <akorotkov@postgresql.org>
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