Re: LWLock deadlock and gdb advice

On Mon, Jun 29, 2015 at 5:55 PM, Peter Geoghegan <pg(at)heroku(dot)com> wrote:

> On Mon, Jun 29, 2015 at 5:37 PM, Jeff Janes <jeff(dot)janes(at)gmail(dot)com> wrote:
> > Is there a way to use gdb to figure out who holds the lock they are
> waiting
> > for?
>
> Have you considered building with LWLOCK_STATS defined, and LOCK_DEBUG
> defined? That might do it.
>

I hadn't planned on running into this problem, so had not compiled
accordingly.

I thought LOCK_DEBUG would produce too much output, but now I see it
doesn't print anything unless Trace_lwlocks is on (but it still makes more
info available to gdb, as Amit mentioned), so I think that should be OK.

Since I messed up the gdb session causing the postmaster to SIGKILL all the
children and destroy the evidence, I'll repeat the run compiled with
LOCK_DEBUG and see what it looks like in the morning.

Thanks,

Jeff