Re: lockup in parallel hash join on dikkop (freebsd 14.0-current)

Hi,

On 2023-02-06 19:51:19 +0100, Tomas Vondra wrote:
> > No. The only thing the machine is doing is
> > 
> >   while /usr/bin/true; do
> >     make check
> >   done
> > 
> > I can't reduce the workload further, because the "join" test is in a
> > separate parallel group (I cut down parallel_schedule). I could make the
> > machine busier, of course.
> > 
> > However, the other lockup I saw was when using serial_schedule, so I
> > guess lower concurrency makes it more likely.
> > 
> 
> FWIW the machine is now on run ~2700 without any further lockups :-/
> 
> Seems it was quite lucky we hit it twice in a handful of attempts.

Did you cut down the workload before you reproduced it the first time, or
after? It's quite possible that it's not reproducible in isolation.

Greetings,

Andres Freund