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Re: Exit walsender before confirming remote flush in logical replication

Andrey Silitskiy <a.silitskiy@postgrespro.ru>

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From: Andrey Silitskiy <a.silitskiy@postgrespro.ru>
To: Alexander Korotkov <aekorotkov@gmail.com>, Fujii Masao <masao.fujii@gmail.com>
Cc: Greg Sabino Mullane <htamfids@gmail.com>, Japin Li <japinli@hotmail.com>, Ronan Dunklau <ronan@dunklau.fr>, Vitaly Davydov <v.davydov@postgrespro.ru>, "Hayato Kuroda (Fujitsu)" <kuroda.hayato@fujitsu.com>, "Takamichi Osumi (Fujitsu)" <osumi.takamichi@fujitsu.com>, "pgsql-hackers@postgresql.org" <pgsql-hackers@postgresql.org>, "sawada.mshk@gmail.com" <sawada.mshk@gmail.com>, "michael@paquier.xyz" <michael@paquier.xyz>, "peter.eisentraut@enterprisedb.com" <peter.eisentraut@enterprisedb.com>, "dilipbalaut@gmail.com" <dilipbalaut@gmail.com>, "andres@anarazel.de" <andres@anarazel.de>, "amit.kapila16@gmail.com" <amit.kapila16@gmail.com>, Kyotaro Horiguchi <horikyota.ntt@gmail.com>, Peter Smith <smithpb2250@gmail.com>
Date: 2026-03-30T03:14:15Z
Lists: pgsql-hackers

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On Mar 29, 2026 Alexander Korotkov <aekorotkov(at)gmail(dot)com> wrote:
 > One possible idea why hand may happen for is is that
 > WalSndWaitForWal() has missing WalSndCheckShutdownTimeout() call.

On Mar 25, 2026 Fujii Masao <masao(dot)fujii(at)gmail(dot)com> wrote:
 > I tested wal_sender_shutdown_timeout under several configurations and
 > encountered a case where the primary shutdown got stuck, ...

Thanks for your help in finding the issue!

I reproduced the problem, in this configuration it turned out that the
walsender was not terminated by wal_sender_shutdown_timeout in
WalSndWaitForWal(), but only when the physical slot was checked for 
inactive flag,
which caused shutdown to hang.

Fix added to the latest patch. Added a perl test-case for this 
configuration.
It is worth noting that in this configuration, the second walsender may
terminate due to inactive slot before the wal_sender_shutdown_timeout
terminates the process, so the test checks timeout termination of only
one walsender.

Regards,
Andrey Silitskiy

Commits

Same data as JSON: GET /api/v1/messages/:b64id/commits the thread's linked commits as JSON, with link sources. API reference →

  1. Avoid blocking indefinitely while finishing walsender shutdown

  2. Add wal_sender_shutdown_timeout GUC to limit shutdown wait for replication

  3. pg_upgrade: Add --copy option

  4. Prevent possibility of panics during shutdown checkpoint.

  5. Support clean switchover.