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From: Anthonin Bonnefoy <anthonin.bonnefoy@datadoghq.com>
Date: Mon, 2 Mar 2026 11:38:06 +0100
Message-ID: 
 <CAO6_Xqp+ADb6KZVWLMALu3xmwVUEO8S1EiCnp38mG6BrHrEnuA@mail.gmail.com>
Subject: Re: Shutdown indefinitely stuck due to unflushed FPI_FOR_HINT record
To: Fujii Masao <masao.fujii@gmail.com>
Cc: PostgreSQL Hackers <pgsql-hackers@postgresql.org>
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On Thu, Feb 26, 2026 at 5:20=E2=80=AFPM Fujii Masao <masao.fujii@gmail.com>=
 wrote:
> Thanks for reporting this issue and for the patch!
>
> I was able to reproduce the problem on master.

Thanks for the confirmation!

> I'm a bit concerned that this approach could cause walwriter to attempt
> WAL writes more aggressively in some cases, adding overhead during
> normal processing. If the goal is only to prevent shutdown from getting s=
tuck,
> instead, would it be sufficient for ShutdownXLOG() to call
> XLogSetAsyncXactLSN() just before WalSndWaitStopping()?

I did something similar with the first version using
XLogFlush(WriteRqstPtr), and it indeed fixes the shutdown issue.

Though I was under the impression that calling XLogSetAsyncXactLSN()
in RecordTransactionAbort was a better approach, as it is similar to
reporting the latest async abort. You may have a large backlog of
records, like selects pruning a lot of pages and timing out, which the
next commit will have to flush. Notifying the walwriter allows it to
flush those records it can.

Maybe for the context of a backport, patching ShutdownXLOG has the
benefit of minimising the amount of changes and risks?

I've updated the RecordTransactionAbort approach for now, with a small
optimization. XactLastRecEnd may be 0 if nothing was written, and we
can skip the unnecessary spinlocks in this case.

Regards,
Anthonin Bonnefoy

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