From: Craig James <craig_james@emolecules.com>
To: jd@commandprompt.com
Cc: pgsql-performance@postgresql.org
Subject: Re: Occasional giant spikes in CPU load
Date: Wed, 07 Apr 2010 14:45:02 -0700
Message-ID: <4BBCFCDE.5020405@emolecules.com> (raw)
In-Reply-To: <1270676410.19131.21.camel@jd-desktop.unknown.charter.com>
References: <k2pda0294261004061437p9cd3810dqe9ce528b6ddb0873@mail.gmail.com>
<m2m603c8f071004071413w1f2d2497hbbe07d9c6491848f@mail.gmail.com>
<4BBCFB12.1010306@emolecules.com>
<1270676410.19131.21.camel@jd-desktop.unknown.charter.com>
On 4/7/10 2:40 PM, Joshua D. Drake wrote:
> On Wed, 2010-04-07 at 14:37 -0700, Craig James wrote:
>> 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.
>
> What does iostat 5 say during the jump?
It's very hard to say ... I'll have to start a background job to watch for a day or so. While it's happening, you can't login, and any open windows become unresponsive. I'll probably have to run it at high priority using nice(1) to get any data at all during the event.
Would vmstat be informative?
Thanks,
Craig
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To: pgsql-performance@postgresql.org
Cc: craig_james@emolecules.com, jd@commandprompt.com
Subject: Re: Occasional giant spikes in CPU load
In-Reply-To: <4BBCFCDE.5020405@emolecules.com>
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