Re: heavy swapping, not sure why

On Mon, Aug 29, 2011 at 3:36 PM, Lonni J Friedman <netllama(at)gmail(dot)com> wrote:
> I have several Linux-x68_64 based dedicated PostgreSQL servers where
> I'm experiencing significant swap usage growth over time.  All of them
> have fairly substantial amounts of RAM (not including swap), yet the
> amount of swap that postgres is using ramps up over time and
> eventually hurts performance badly.  In every case, simply restarting
> postgresql frees up all the swap in use (until it ramps up again
> later).  I'm assuming that I have at least one postgresql.conf
> parameter set wrong, but I'm not sure which.  I read that
> (max_connections * work_mem) should never exceed physical RAM, and if
> that's accurate, then I suspect that's the root of my problem on
> systemA (below).  However, I'd like confirmation before I start
> tweaking things, as one of these servers is in production, and I can't
> easily tweak settings to experiment (plus this problem takes a few
> weeks before swapping gets bad enough to impact performance).

using any C code in the backend? this includes 3rd party libraries
which link in C, including postgis, pljava, xml2, etc. Any features
being used not included in the standard core distribution are
interesting.

How long do your database connections stay open? forever? If yes, is
memory distributed semi-evenly across all postgres processes or only
to particular ones? If no, do you see excessive consumption with the
non user backends like the stats collector, etc?

Anything else running on these boxes? Application server? Anything
written in java?

merlin