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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: Fujii Masao <masao.fujii@gmail.com>
Cc: Alexander Korotkov <aekorotkov@gmail.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>, Greg Sabino Mullane <htamfids@gmail.com>, Japin Li <japinli@hotmail.com>
Date: 2026-03-13T12:14:07Z
Lists: pgsql-hackers 
On Fri, 13 Mar 2026 Fujii Masao <masao(dot)fujii(at)gmail(dot)com> wrote:
 > With the patch, when I set wal_sender_shutdown_timeout to 1ms and
 > wal_sender_timeout to 1min, it still took about 26s for walsender to shut
 > down due to wal_sender_shutdown_timeout expiration.

Thanks!.

I also reproduced this delay in case of full output buffers. It has already
been fixed in the latest patch.
I think in your case, the 26-second wait was due to walsender falling asleep
at wal_sender_timeout / 2 seconds after receiving the shutdown request.
The issue should have been fixed in the patch (see WalSndComputeSleeptime).

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.