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

Amit Kapila <amit.kapila16@gmail.com>

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From: Amit Kapila <amit.kapila16@gmail.com>
To: Fujii Masao <masao.fujii@gmail.com>
Cc: PostgreSQL Hackers <pgsql-hackers@lists.postgresql.org>
Date: 2026-03-21T16:52:31Z
Lists: pgsql-hackers 
On Wed, Mar 18, 2026 at 9:35 PM Fujii Masao <masao.fujii@gmail.com> wrote:
>
> 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?
>

IIRC, this same signal is used for both the backend executing
pg_sync_replication_slots() and slotsync worker. We want the worker to
exit and error_out backend. Using SIGTERM for backend could result in
its exit. Also, we want the last slotsync cycle to complete before
promotion so that chances of subscribers that do failover/switchover
to new primary has better chances of finding failover slots
sync-ready.

-- 
With Regards,
Amit Kapila.

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.