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

On 8/22/25 08:30, hubert depesz lubaczewski wrote:
> On Fri, Aug 22, 2025 at 11:21:22AM -0400, Tom Lane wrote:
>> hubert depesz lubaczewski <depesz(at)depesz(dot)com> writes:
>>> I got repeatable case today. Is is breaking on its own everyy
>>> ~ 5 minutes.
>>
>> Interesting. That futex call is presumably caused by interaction
>> with some other process within the standby server, and the only
>> plausible candidate really is the startup process (which is replaying
>> WAL received from the primary). There are cases where WAL replay
>> will take locks that can block queries on the standby. Can you
>> correlate the delays on the standby server with any DDL events
>> occurring on the primary?
>
> Nope. Plus there is certain repetition of these cases, so even if I'd
> miss *some* create table/alter, it just isn't going to be happening
> every 4-5 minutes.
>

> So, while there are outliers, I'd say that most of the problems happens every
> 3-5 minutes.

Are you using the Postgres community version or the AWS variant?

>
> depesz
>

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