MIME-Version: 1.0
References: 
 <CAHGQGwFzNYroAxSoyJhqTU-pH=t4Ej6RyvhVmBZ91Exj_TPMMQ@mail.gmail.com>
 <CAA4eK1+CrQNqiPDKv1wYfdkbX0FARJoi1=0ioaAqkLzbq2vG1w@mail.gmail.com>
 <CAHGQGwHABvuCoyM24HUiFZ5oJq_CoFomjt_cqD-0cJLMjFXJjQ@mail.gmail.com>
In-Reply-To: 
 <CAHGQGwHABvuCoyM24HUiFZ5oJq_CoFomjt_cqD-0cJLMjFXJjQ@mail.gmail.com>
From: Amit Kapila <amit.kapila16@gmail.com>
Date: Thu, 26 Mar 2026 15:40:10 +0530
Message-ID: 
 <CAA4eK1LzZGfRANPAnv6NpKCH2ENuZO6HswgY14A=xsOXmucPhw@mail.gmail.com>
Subject: Re: Use SIGTERM instead of SIGUSR1 for slotsync worker to exit during
 promotion?
To: Fujii Masao <masao.fujii@gmail.com>
Cc: PostgreSQL Hackers <pgsql-hackers@lists.postgresql.org>
Content-Type: text/plain; charset="UTF-8"
Content-Transfer-Encoding: quoted-printable
Archived-At: 
 <https://www.postgresql.org/message-id/CAA4eK1LzZGfRANPAnv6NpKCH2ENuZO6HswgY14A%3DxsOXmucPhw%40mail.gmail.com>
Precedence: bulk

On Mon, Mar 23, 2026 at 11:21=E2=80=AFAM Fujii Masao <masao.fujii@gmail.com=
> wrote:
>
> On Sun, Mar 22, 2026 at 1:52=E2=80=AFAM Amit Kapila <amit.kapila16@gmail.=
com> wrote:
> >
> > On Wed, Mar 18, 2026 at 9:35=E2=80=AFPM Fujii Masao <masao.fujii@gmail.=
com> wrote:
> > >
> > > I noticed that during standby promotion the startup process sends SIG=
USR1 to
> > > the slotsync worker to make it exit. Is there a reason for using SIGU=
SR1?
> > >
> >
> > 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.
>
> Why do we want the backend running pg_sync_replication_slots() to throw
> an error here, rather than just exit? If emitting an error is really requ=
ired,
> another option would be to store the process type in SlotSyncCtx and send
> different signals accordingly, for example, SIGTERM for the slotsync work=
er
> and another signal for a backend. But it seems simpler and sufficient to =
have
> the backend exit in this case as well.
>

As we want to retain the existing behavior for API, so instead of
using two signals, we can achieve what you intend to achieve by one
signal (SIGUSR1) only. We can use SendProcSignal mechanism as is used
ParallelWorkerShutdown. On promotion, we send a SIGUSR1 signal to
slotsync worker/backend via SendProcSignal. Then in
procsignal_sigusr1_handler(), it will call HandleSlotSyncInterrupt.
HandleSlotSyncInterrupt() will set the InterruptPending and
SlotSyncPending flag. Then ProcessInterrupt() will call a slotsync
specific function based on the flag and do what we currently do in
ProcessSlotSyncInterrupts. I think this should address the issue you
are worried about.

--=20
With Regards,
Amit Kapila.