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Re: Use SIGTERM instead of SIGUSR1 for slotsync worker to exit during promotion?

Tom Lane <tgl@sss.pgh.pa.us>

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From: Tom Lane <tgl@sss.pgh.pa.us>
To: Fujii Masao <masao.fujii@gmail.com>
Cc: PostgreSQL Hackers <pgsql-hackers@lists.postgresql.org>
Date: 2026-03-18T16:23:51Z
Lists: pgsql-hackers 
Fujii Masao <masao.fujii@gmail.com> writes:
> I noticed that during standby promotion the startup process sends SIGUSR1 to
> the slotsync worker to make it exit. Is there a reason for using SIGUSR1?
> Would it make sense to send SIGTERM instead, so the worker can exit promptly
> even while waiting?

One consideration here is that we expect all processes to receive
SIGTERM from init at the beginning of an operating system shutdown
sequence.  Background workers should exit at that point only if their
services will not be needed during database shutdown.  While it
sounds plausible that a slotsync worker should exit immediately,
I'm not quite sure if that's what we want.

			regards, tom lane

Commits

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

  1. Update .abi-compliance-history for change to enum ProcSignalReason

  2. Fix ABI break by moving PROCSIG_SLOTSYNC_MESSAGE in ProcSignalReason

  3. Fix slotsync worker blocking promotion when stuck in wait

  4. Add retry logic to pg_sync_replication_slots().

  5. Enhance slot synchronization API to respect promotion signal.