Re: backends stuck in "startup"

Hi,

On 2017-11-21 17:09:26 -0600, Justin Pryzby wrote:
> I'm sorry to report this previously reported problem is happening again,
> starting shortly after pg_upgrading a customer to PG10.1 from 9.6.5.
>
> As $subject: backends are stuck in startup for minutes at a time. I didn't
> strace this time, but I believe last time I saw one was waiting in a futex.

Could you try stracing next time? Don't think it's conclusive that
they're all continually waiting rather than contending on a few locks.
As soon as you attach to one backend a contended lock situation can
quickly turn into standstill if you end up interrupting a process that
holds a lock.

> - we DO use temp tables; it looks like we created up to 90 temp tables each hour;

Doesn't quite seem enough to cause problems.

> - I'm planning do disable sync seqscan for the night (although as I understand
> that may not matter (?))

I doubt it matters here.

Greetings,

Andres Freund