Re: autovac hung/blocked

On Tue, Nov 14, 2006 at 12:53:56PM -0700, Ed L. wrote:
> On Tuesday November 14 2006 12:49 pm, Jim C. Nasby wrote:
> > On Tue, Nov 14, 2006 at 11:20:30AM -0700, Ed L. wrote:
> > > I have an 8.1.2 autovac which appears to be hanging/blocking
> > > every few days or so, but we're don't understand what's
> > > causing it. I wasn't able to catch a backtrace before we
> > > killed it. I do not see autovac locks in the pg_locks view.
> > >
> > > Will running 8.1.5 buy me anything in terms of being able to
> > > see what it has locked and what locks it might be awaiting?
> > > Or maybe in terms of bugs that might explain it?
> >
> > If there's no locks, why do you think it's blocked?
>
> I had wondered if all autovac locks were in the pg_locks view,
> but I now see them. A gdb backtrace a few days ago had autovac
> waiting on a semaphore, and I assumed that was waiting on a
> lock.

Well, vacuum shouldn't really block on much... DDL and LOCK TABLE are
the only things I can think of off the top of my head.

You don't have the vacuum cost delay settings set unreasonably high, do
you?
--
Jim Nasby jim(at)nasby(dot)net
EnterpriseDB http://enterprisedb.com 512.569.9461 (cell)