Re: Load spikes on 8.1.11

On Tue, Jul 22, 2008 at 1:29 AM, Andrew Sullivan <ajs(at)commandprompt(dot)com>
wrote:

> On Sat, Jul 19, 2008 at 07:09:46AM +0530, Gurjeet Singh wrote:
>
> > Will try this option, at least in the next schema upgrade or when setting
> up
> > Slony.
>
> As I've already suggested, however, if you try to set up slony on a
> loaded database, you're going to see all manner of problems. Slony
> takes some heavy-duty locks when it does its setup work. It's
> designed that you should have an application outage for this sort of
> work. Please see previous discussion on the Slony mailing list.

Well, a very low activity period of the application (after 11 PM EST) is
chosen as the maintenance window. The application is not down, but has just
the connections open, and almost all of them sitting <IDLE>.

I am aware of the heavy locking involved with Slony, which should mean that
it blocks the application connections; that's be completely acceptable,
given all the warnings in the Slony docs. But what I am concerned about and
trying to hunt down is why <IDLE> backend processes are all consuming up all
of CPU (!!!) so much so that I am unable to fire up any new process!

Another possible cause we are looking at now is the role Xeon hyperthreading
can play here. Will keep you all updated.

Thanks and best regards,
--
gurjeet[(dot)singh](at)EnterpriseDB(dot)com
singh(dot)gurjeet(at){ gmail | hotmail | indiatimes | yahoo }.com

EnterpriseDB http://www.enterprisedb.com

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