Re: Postgres entering zombie state once a week in production evnvironment

Στις Tuesday 14 April 2009 09:25:54 ο/η Bryce Nesbitt έγραψε:
> We have a medium scale installation of Postgres 8.3 that is freezing
> about once a week. I'm looking for any hints on how to diagnose the
> situation, as nothing is logged.
>
> The system is matched pair of Sunfire servers, running Debian Etch with
> a 2.6.18-6-amd64 kernel, PostgreSQL 8.3.4, and DRBD 8.0.13.
>
> During a failed state, pg_stat_activity will show hundreds of statements
> pending. query_start will show the statements arriving at a normal rate
> (a few per second), but clearly they never complete. The bulk of these
> statement are a simple select that starts each web session, a statement
> that generally completes in tenths of milliseconds. Restarting postgres
> restores normal operation, at the loss of all chance of figuring out
> what was wrong.
>
> postgresql.conf has customized:
> log_destination = 'syslog'
> log_min_error_statement = error
> log_min_duration_statement = 5000
>
> Where can I go from here? I'm turning on log_checkpoints now, though
> all I see is "postgres[14412]: [4-1] LOG: checkpoint starting: time"
> with no actual time printed.
>
>

Did you check for locks?
SELECT * from pg_locks;
SELECT l.locktype,c.relname,l.pid,l.mode from pg_locks l,pg_class c where l.relation=c.oid ;
Were you able to issue other select commands during the problem? Were you able to start psql and do some simple command?
Have you ruled out the possibility of the application being locked for other reasons? (limits, network failure,etc....)

--
Achilleas Mantzios