Re: Recent 027_streaming_regress.pl hangs

On 2024-08-11 Su 8:32 PM, Tom Lane wrote:
> Andrew Dunstan<andrew(at)dunslane(dot)net> writes:
>> We'll see. I have switched crake from --run-parallel mode to --run-all
>> mode i.e. the runs are serialized. Maybe that will be enough to stop the
>> errors. I'm still annoyed that this test is susceptible to load, if that
>> is indeed what is the issue.
> crake is still timing out intermittently on 027_streaming_regress.pl,
> so that wasn't it. I think we need more data. We know that the
> wait_for_catchup query is never getting to true:
>
> SELECT '$target_lsn' <= ${mode}_lsn AND state = 'streaming'
>
> but we don't know if the LSN condition or the state condition is
> what is failing. And if it is the LSN condition, it'd be good
> to see the actual last LSN, so we can look for patterns like
> whether there is a page boundary crossing involved. So I suggest
> adding something like the attached.
>
> If we do this, I'd be inclined to instrument wait_for_slot_catchup
> and wait_for_subscription_sync similarly, but I thought I'd check
> for contrary opinions first.
>
>

Seems reasonable.

cheers

andrew

--
Andrew Dunstan
EDB:https://www.enterprisedb.com