"Arthur Ward" <award@dominionsciences.com> writes:
> 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.
How verbose are your Postgres logging settings?
On most platforms I've dealt with, syslog drops messages on the floor if
it starts to get saturated. It may be that the Linux implementation has
worse behavior than that under heavy load :-(. In any case I'd suggest
filing a bug against syslog. There's very little we can do about it if
the syslog library call hangs up.
Personally I find it more reliable to pipe the postmaster's stderr to
some sort of log-rotation program than to depend on syslog. It seems
that the Apache folks have found the same, since they include a suitable
log-rotation filter in their distribution ...
regards, tom lane