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In-Reply-To: <aecRYWJmfQnuVDBe@paquier.xyz>
From: JoongHyuk Shin <sjh910805@gmail.com>
Date: Mon, 27 Apr 2026 20:07:17 +0900
Message-ID: 
 <CACSdjfPpwYcMAs6PdT9LQtxSNoiMZjrSfTNe5bOEvVB105Hzww@mail.gmail.com>
Subject: Re: [PATCH] Prevent repeated deadlock-check signals in standby buffer
 pin waits
To: Michael Paquier <michael@paquier.xyz>
Cc: Fujii Masao <masao.fujii@gmail.com>,
	"pgsql-hackers@lists.postgresql.org" <pgsql-hackers@lists.postgresql.org>
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Thanks for the review.
v2 attached, with the suggested initialization added for symmetry.

Agreed this is an improvement rather than a bug fix,
so I've updated the CF tag to Performance accordingly.

I also verified the fix locally on a primary-standby setup,
using the buffer-pin conflict scenario from src/test/recovery/t/
031_recovery_conflict.pl
(aborted INSERT + cursor on standby + VACUUM FREEZE on primary).
On master, strace showed 9 SIGUSR1 broadcasts to the conflicting backend
over a 10-second window (one per deadlock_timeout).
With the patch applied, only 1 broadcast over the same window.

Patch attached.

--
JoongHyuk Shin

On Tue, Apr 21, 2026 at 2:55=E2=80=AFPM Michael Paquier <michael@paquier.xy=
z> wrote:

> On Tue, Apr 21, 2026 at 02:42:38PM +0900, Fujii Masao wrote:
> > Since this change improves recovery-conflict behavior rather than fixin=
g
> 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).
> --
> Michael
>

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<div dir=3D"ltr">Thanks for the review.<br>v2 attached, with the suggested =
initialization added for symmetry.<br><br>Agreed this is an improvement rat=
her than a bug fix,<br>so I&#39;ve updated the CF tag to Performance accord=
ingly.<br><br>I also verified the fix locally on a primary-standby setup,<b=
r>using the buffer-pin conflict scenario from src/test/recovery/t/<a href=
=3D"http://031_recovery_conflict.pl">031_recovery_conflict.pl</a><br>(abort=
ed INSERT + cursor on standby + VACUUM FREEZE on primary).<br>On master, st=
race showed 9 SIGUSR1 broadcasts to the conflicting backend<br>over a 10-se=
cond window (one per deadlock_timeout).<br>With the patch applied, only 1 b=
roadcast over the same window.<br><br>Patch attached.<br><br>--<br>JoongHyu=
k Shin</div><br><div class=3D"gmail_quote gmail_quote_container"><div dir=
=3D"ltr" class=3D"gmail_attr">On Tue, Apr 21, 2026 at 2:55=E2=80=AFPM Micha=
el Paquier &lt;<a href=3D"mailto:michael@paquier.xyz">michael@paquier.xyz</=
a>&gt; wrote:<br></div><blockquote class=3D"gmail_quote" style=3D"margin:0p=
x 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex">On=
 Tue, Apr 21, 2026 at 02:42:38PM +0900, Fujii Masao wrote:<br>
&gt; Since this change improves recovery-conflict behavior rather than fixi=
ng a bug,<br>
&gt; it doesn&#39;t seem to need backpatching and we may need to wait until=
 v20<br>
&gt; development opens (probably July) before committing it.<br>
<br>
Yeah, this one is an improvement, not an actual bug, so let&#39;s wait for<=
br>
v20 if worth doing (I did not check it). <br>
--<br>
Michael<br>
</blockquote></div>

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