Horton

Re: LISTEN/NOTIFY bug: VACUUM sets frozenxid past a xid in async queue

Matheus Alcantara <matheusssilv97@gmail.com>

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From: "Matheus Alcantara" <matheusssilv97@gmail.com>
To: "Rishu Bagga" <rishu.postgres@gmail.com>, "Arseniy Mukhin" <arseniy.mukhin.dev@gmail.com>
Cc: "Yura Sokolov" <y.sokolov@postgrespro.ru>, "Masahiko Sawada" <sawada.mshk@gmail.com>, "Daniil Davydov" <3danissimo@gmail.com>, Álvaro Herrera <alvherre@kurilemu.de>, "Alexandra Wang" <alexandra.wang.oss@gmail.com>, "PostgreSQL Hackers" <pgsql-hackers@postgresql.org>, "Tom Lane" <tgl@sss.pgh.pa.us>, "Joel Jacobson" <joel@compiler.org>
Date: 2025-09-05T10:45:32Z
Lists: pgsql-hackers

Commits

Same data as JSON: GET /api/v1/messages/:b64id/commits the thread's linked commits as JSON, with link sources. API reference →

  1. Clear 'xid' in dummy async notify entries written to fill up pages

  2. Fix remaining race condition with CLOG truncation and LISTEN/NOTIFY

  3. Fix bug where we truncated CLOG that was still needed by LISTEN/NOTIFY

  4. Escalate ERRORs during async notify processing to FATAL

  5. Limit the size of TID lists during parallel GIN build

On Thu Sep 4, 2025 at 8:02 PM -03, Rishu Bagga wrote:
> On Thu, Sep 4, 2025 at 7:14 AM Arseniy Mukhin
> <arseniy.mukhin.dev@gmail.com> wrote:
>
>> Interesting, have you shared your patch and results somewhere? IIUC
>> Tom's approach resolves this bug, because with it we have queue
>> entries produced by committed transactions only, so we don't need to
>> check their status and don't have dependency on clog.
>
> I was eventually able to get better numbers with the patch after using
> a substantial number of connections, so I have now posted it here. [1].
>
Thanks for sharing the patch! I'll reserve some time to test and review.

--
Matheus Alcantara