Re: [PATCH] Prevent repeated deadlock-check signals in standby buffer pin waits

Hello.

Same function, different races, I think.
Vitaly reports a missed wake-up where deadlock_timeout never fires
(spurious SIGALRM from log_startup_progress_interval plus the lazy
setitimer in 09cf1d52).
This patch addresses the opposite,
deadlock_timeout does fire, but LockBufferForCleanup loops back and re-arms
it,
so the signal repeats once per second.

The two fixes do not overlap
(the added ProcWaitForSignal sits inside the deadlock branch that Vitaly's
scenario never reaches).

--
JH Shin

On Wed, May 20, 2026 at 7:15 AM Álvaro Herrera <alvherre(at)kurilemu(dot)de> wrote:

> Hello,
>
> On 2026-Apr-21, Michael Paquier wrote:
>
> > On Tue, Apr 21, 2026 at 02:42:38PM +0900, Fujii Masao wrote:
> > > Since this change improves recovery-conflict behavior rather than
> fixing a bug,
> > > it doesn't seem to need backpatching and we may need to wait until v20
> > > development opens (probably July) before committing it.
> >
> > Yeah, this one is an improvement, not an actual bug, so let's wait for
> > v20 if worth doing (I did not check it).
>
> Hmm, is this related to
> https://postgr.es/m/44c24dcf-5710-410f-b1b6-d10b315f3d51@postgrespro.ru ?
> In there, Vitaly claims to be reporting a bug that goes back to pg15,
> which contradicts this assessment.
>
> Regards,
>
> --
> Álvaro Herrera Breisgau, Deutschland —
> https://www.EnterpriseDB.com/
> "¿Qué importan los años? Lo que realmente importa es comprobar que
> a fin de cuentas la mejor edad de la vida es estar vivo" (Mafalda)
>