On Sat, Aug 07, 2021 at 04:44:07PM -0700, Andres Freund wrote: > > As currently implemented those pgstat_get_my_query_id() calls are not > safe. It's fine during backend startup because MyBEEntry is not set, but > during shutdown that's not ok, because we never unset MyBEEntry. > > andres@awork3:~/src/postgresql$ > /home/andres/build/postgres/dev-assert/vpath/src/backend/postgres --single > postgres -D /srv/dev/pgdev-dev/ -c 'log_line_prefix=%Q' -c > log_min_messages=debug1 > [...] > PostgreSQL stand-alone backend 15devel > backend> 0NOTICE: shutting down > 0DEBUG: performing replication slot checkpoint > Segmentation fault
Ouch > I suspect that to make the elog.c usage safe, we'll have to clear MyBEEntry in > pgstat_beshutdown_hook(). I agree, and a quick test indeed fix your scenario. It also seems like a good thing to do overall. I didn't find any other problematic corner cases, but I'm not that familiar with pgstat, especially after the recent activity.
