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

From: "Joel Jacobson" <joel(at)compiler(dot)org>
To: "Heikki Linnakangas" <hlinnaka(at)iki(dot)fi>, "Tom Lane" <tgl(at)sss(dot)pgh(dot)pa(dot)us>
Cc: pgsql-hackers <pgsql-hackers(at)postgresql(dot)org>
Subject: Re: LISTEN/NOTIFY bug: VACUUM sets frozenxid past a xid in async queue
Date: 2025-10-30 23:27:11
Message-ID: c37cae90-0564-4798-89e1-5dfb8c6d2cba@app.fastmail.com
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On Fri, Oct 31, 2025, at 00:08, Joel Jacobson wrote:
> On Thu, Oct 30, 2025, at 14:25, Heikki Linnakangas wrote:
>> Joel, since you've been working on some optimizations in this area too,
>> would you happen to have some suitable performance test scripts for this?
>
> Glad you asked. I'm actually working on a benchmark+correctness tester.
> It's very much work-in-progress though, don't look too much at the code,
> or your eyes will bleed.
>
> It's a combined benchmark + correctness tester, that verifies that only
> the expected notifications are received on the expected connections,
> while at the same time doing timing measurements.

To run multiple pg_bench_lino processes in parallell to simulate
concurrent workloads, I realized the randomization of the channel names
and payloads were not random enough to avoid collissions. New version
attached that uses real UUIDs for channel names and payloads.

/Joel

Attachment Content-Type Size
v2-pg_bench_lino.c application/octet-stream 33.6 KB

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