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Re: Adding locks statistics

Bertrand Drouvot <bertranddrouvot.pg@gmail.com>

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From: Bertrand Drouvot <bertranddrouvot.pg@gmail.com>
To: Michael Paquier <michael@paquier.xyz>
Cc: Andres Freund <andres@anarazel.de>, Jeff Davis <pgsql@j-davis.com>, Greg Sabino Mullane <htamfids@gmail.com>, pgsql-hackers@lists.postgresql.org
Date: 2026-03-25T03:15:19Z
Lists: pgsql-hackers 
Hi,

On Wed, Mar 25, 2026 at 08:46:23AM +0900, Michael Paquier wrote:
> On Tue, Mar 24, 2026 at 04:09:37PM -0400, Andres Freund wrote:
> > The test is extremely unstable on windows.  On CI 10/16 runs since the test in
> > failed due to it, afaict.

Thanks for the warning!

> I am not surprised by that.  Windows is good in catching race
> conditions.
> 
> > I don't see how a test with a timeout setting that's anywhere remotely close
> > to 10ms could be expected to be stable.
> 
> Well, the low value of deadlock_timeout is not the problem. 

Yeah, there are other tests making use of a 10ms deadlock timeout.

> This test would be better if rewritten as a TAP test, I guess, with a
> NOTICE injection point before the CheckDeadLock() call in ProcSleep()
> to make sure that the second session processes the deadlock timeout
> request while it is waiting on its lock to be acquired.  One trickier
> part is that we only care about the deadlock_timeout in s2, because we
> want to measure the wait it has waited until the lock could be
> acquired, meaning that we should make s1 use a large deadlock_timeout
> to avoid interferences with a global injpoint.
> 
> I don't have the credits to test that in the CI for this month,
> unfortunately, and this creates noise in the CI for the work of other
> folks in this release cycle, so I am going to remove this test for
> now.

Thanks for the test removal. I created an open item for v19 so that we
don't forget to re-add a new version of the tests. I'll work on it.

[1]: https://wiki.postgresql.org/wiki/PostgreSQL_19_Open_Items

Regards,

-- 
Bertrand Drouvot
PostgreSQL Contributors Team
RDS Open Source Databases
Amazon Web Services: https://aws.amazon.com

Commits

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

  1. Fix injection point detach timing problem in TAP test for lock stats

  2. Use single LWLock for lock statistics in pgstats

  3. Add tests for lock statistics, take two

  4. Remove isolation test lock-stats

  5. Avoid including clog.h in proc.h

  6. Don't include storage/lock.h in so many headers

  7. Add support for lock statistics in pgstats

  8. Move some code blocks in lock.c and proc.c

  9. Move declarations related to locktags from lock.h to new locktag.h