Re: Printing backtrace of postgres processes

On Thu, Jan 21, 2021 at 7:26 AM Tom Lane <tgl@sss.pgh.pa.us> wrote:
>
> Craig Ringer <craig.ringer@enterprisedb.com> writes:
> > On Wed, 20 Jan 2021 at 05:23, Tom Lane <tgl@sss.pgh.pa.us> wrote:
> >> BTW, it also looks like the patch is doing nothing to prevent the
> >> backtrace from being sent to the connected client.
>
> > I don't see a good reason to send a bt to a client. Even though these
> > backtraces won't be analysing debuginfo and populating args, locals, etc,
> > it should still just go to the server log.
>
> Yeah.  That's easier than I was thinking, we just need to
> s/LOG/LOG_SERVER_ONLY/.
>
> >> Maybe, given all of these things, we should forget using elog at
> >> all and just emit the trace with fprintf(stderr).
>
> > That causes quite a lot of pain with MemoryContextStats() already
>
> True.  Given the changes discussed in the last couple messages, I don't
> see any really killer reasons why we can't ship the trace through elog.
> We can always try that first, and back off to fprintf if we do find
> reasons why it's too unstable.
>

Thanks all of them for the suggestions. Attached v3 patch which has
fixes based on the suggestions. It includes the following fixes: 1)
Removal of support to get callstack of all postgres process, user can
get only one process callstack. 2) Update the documentation. 3) Added
necessary checks for pg_print_callstack similar to
pg_terminate_backend. 4) Changed LOG to LOG_SERVER_ONLY.
Thoughts?

Regards,
Vignesh