On 4/7/10 2:59 PM, Tom Lane wrote:
Craig James<craig_james@xxxxxxxxxxxxxx> writes:
Most of the time Postgres runs nicely, but two or three times a day we get a huge spike in the CPU load that lasts just a short time -- it jumps to 10-20 CPU loads. Today it hit 100 CPU loads. Sometimes days go by with no spike events. During these spikes, the system is completely unresponsive (you can't even login via ssh).
I managed to capture one such event using top(1) with the "batch" option as a background process. See output below - it shows 19 active postgress processes, but I think it missed the bulk of the spike.
Any ideas where I can look to find what's triggering this?
Postgres 8.3.0
^^^^^
If it's really 8.3.0, try updating to 8.3.something-recent. We've fixed
a whole lot of bugs since then.
Good advice, I've been meaning to do this, maybe this will be a kick in the pants to motivate me.
I have a suspicion that this might be an sinval overrun scenario, in
which case you'd need to update to 8.4 to get a real fix. But updating
in the 8.3 branch would be cheap and easy.
If it is sinval overrun, it would presumably be triggered by a whole lot
of catalog changes being made at approximately the same time. Can you
correlate the spikes with anything like that?
Not that I know of. Just regular web traffic. On the backup server these events happen occasionally even when there is little or no web traffic, and nobody logged in doing maintenance.
regards, tom lane
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