I'm encountering strange hangs in postgresql backends at random moments.
They seem to be associated with attempts to issue log entries via syslog.
I have run backtraces on the hung backends a few times, and they routinely
trace into system libraries where it looks like a stuck syslog call. So
far, I haven't had this problem with any other apps, so I'm thinking it's
a condition being aggravated by Postgres.
The machines I'm seeing this on are RedHat 8 and Gentoo Linux machines
(x86). We're running compiled-from-source 7.3.3 on both machines (by hand
on the RH8 machine, and built by Gentoo's package manager, because it's a
build-from-source distribution). On my Gentoo test boxes, it happens
occasionally using syslog-ng 1.6.0_rc3 and glibc 2.3.2-r1. On the RedHat 8
machine, it's sysklogd-1.4.1-10 and "glibc-devel-2.3.2-4.80.6". I switched
to not using syslog on the RH8 machine because it was hanging backends
quite regularly, and that's rather bad in production. :)
Has anyone else had problems using the syslog option?
I need to rebuild PostgreSQL on my test machine so I'll have unstripped
binaries, but once that's done, I'll bring on the stack traces when I get
another hang.