Re: Load spikes on 8.1.11

On Fri, Jul 18, 2008 at 10:05 AM, Gurjeet Singh <singh(dot)gurjeet(at)gmail(dot)com>
wrote:

> On Fri, Jul 18, 2008 at 9:58 AM, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:
>
>> "Gurjeet Singh" <singh(dot)gurjeet(at)gmail(dot)com> writes:
>> > During these spikes, in the 'top' sessions we see the 'idle' PG
>> > processes consuming between 2 and 5 % CPU, and since the box has 8 CPUS
>> (2
>> > sockets and each CPU is a quad core Intel Xeon processors) and somewhere
>> > around 200 Postgres processes, the load spikes to above 200; and it does
>> > this very sharply.
>>
>> This looks like heavy contention for a spinlock. You need to get a
>> higher-level analysis of what's happening before anyone can say much
>> more than that.
>>
>> Note that 8.1 is pretty much ancient history as far as scalability to
>> 8-core hardware goes. You should probably consider updating to 8.3
>> before investing too much time in tracking down what's happening.
>> If you can still show the problem on 8.3 then there would be some
>> interest in fixing it ...
>
>
> Upgrading is on the cards, but not as high priority as I would like it to
> be! This is a production box, and we desperatly need some respite from these
> spikes.
>
> Can you please elaborate on what high level diagnosis would you need?
>
> I just ran DROP SCHEMA _<slony schema> CASCADE; and it spiked again, on a
> very low loaded box!!
>
> Thanks for all you help.
>

Would reducing the number of connections on the DB help in reducing the
spike?

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