Re: Streaming replica hangs periodically for ~ 1 second - how to diagnose/debug

On 8/21/25 09:51, hubert depesz lubaczewski wrote:
> On Thu, Aug 21, 2025 at 08:59:03AM -0700, Adrian Klaver wrote:
>> Getting to the bottom of the bag of ideas:
>> Have you looked at the OS system log for the time period involved?
>
> Yes. Mostly dmesg. Nothing interesting logged around the time.
>
>> You mentioned this seemed to involve PREPARE and DISCARD ALL.
>> Is this the same set of statements or is it all over the place?
>
> No. From what I can tell it's random sample.
>
>> Also it would be helpful to know what bouncer you are actually using and
>> what mode you are running in?
>
> pgBouncer, version 1.23.1. As for more... mostly transaction pooling.
> Applications go using transaction pooling, but people (dbas, ops) have
> session pooling.

Have you looked at?:

https://www.pgbouncer.org/changelog.html#pgbouncer-124x

To see if anything stands out.

Then there is:

https://www.pgbouncer.org/config.html#max_prepared_statements

The below may also be worth looking at:

https://github.com/pgbouncer/pgbouncer/pull/1144

I can't help thinking that there is a caching issue at stake, though
that is just a guess.

>
> Best regards,
>
> depesz
>

--
Adrian Klaver
adrian(dot)klaver(at)aklaver(dot)com