From: | Bharath Rupireddy <bharath(dot)rupireddyforpostgres(at)gmail(dot)com> |
---|---|
To: | Andres Freund <andres(at)anarazel(dot)de> |
Cc: | Michael Paquier <michael(at)paquier(dot)xyz>, Heikki Linnakangas <hlinnaka(at)iki(dot)fi>, Nathan Bossart <nathandbossart(at)gmail(dot)com>, PostgreSQL Hackers <pgsql-hackers(at)lists(dot)postgresql(dot)org> |
Subject: | Re: WAL Insertion Lock Improvements |
Date: | 2023-07-28 11:27:18 |
Message-ID: | CALj2ACUsNGP2Bgd-jjK10T3P6hf0rG8hGsqGEmyJ9mnoM-vXdw@mail.gmail.com |
Views: | Raw Message | Whole Thread | Download mbox | Resend email |
Thread: | |
Lists: | pgsql-hackers |
On Wed, Jul 26, 2023 at 1:27 AM Andres Freund <andres(at)anarazel(dot)de> wrote:
>
> > 0001 has been now applied. I have done more tests while looking at
> > this patch since yesterday and was surprised to see higher TPS numbers
> > on HEAD with the same tests as previously, and the patch was still
> > shining with more than 256 clients.
>
> Just a small heads up:
>
> I just rebased my aio tree over the commit and promptly, on the first run, saw
> a hang. I did some debugging on that. Unfortunately repeated runs haven't
> repeated that hang, despite quite a bit of trying.
Hm. Please share workload details, test scripts, system info and any
special settings for running in my setup.
> The symptom I was seeing is that all running backends were stuck in
> LWLockWaitForVar(), even though the value they're waiting for had
> changed. Which obviously "shouldn't be possible".
Were the backends stuck there indefinitely? IOW, did they get into a deadlock?
> It's of course possible that this is AIO specific, but I didn't see anything
> in stacks to suggest that.
>
> I do wonder if this possibly exposed an undocumented prior dependency on the
> value update always happening under the list lock.
I'm going through the other thread mentioned by Michael Paquier. I'm
wondering if the deadlock issue illustrated here
https://www.postgresql.org/message-id/55BB50D3.9000702%40iki.fi is
showing up again, because 71e4cc6b8e reduced the contention on
waitlist lock and made things *a bit* faster.
--
Bharath Rupireddy
PostgreSQL Contributors Team
RDS Open Source Databases
Amazon Web Services: https://aws.amazon.com
From | Date | Subject | |
---|---|---|---|
Next Message | Noah Misch | 2023-07-28 11:42:14 | Re: Postgres v15 windows bincheck regression test failures |
Previous Message | Matthias van de Meent | 2023-07-28 11:11:47 | Re: Optimizing nbtree ScalarArrayOp execution, allowing multi-column ordered scans, skip scan |