Re: backends stuck in "startup"

On 2017-11-21 18:50:05 -0500, Tom Lane wrote:
> Andres Freund <andres(at)anarazel(dot)de> writes:
> > On 2017-11-21 18:21:16 -0500, Tom Lane wrote:
> >> Justin Pryzby <pryzby(at)telsasoft(dot)com> writes:
> >>> 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.
>
> > A futex? Hm, that was stock postgres?
>
> Sure, since we switched to unnamed-POSIX semaphores in v10. On Linux
> those are futexes.

> (If Justin saw that while still on 9.6, then it'd be worth looking
> closer.)

Right. I took this to be referring to something before the current
migration, but I might have overinterpreted things. There've been
various forks/ports of pg around that had hand-coded replacements with
futex usage, and there were definitely buggy versions going around a few
years back.

Greetings,

Andres Freund