Re: backend suddenly becomes slow, then remains slow - Mailing list pgsql-performance

From Andrew Dunstan
Subject Re: backend suddenly becomes slow, then remains slow
Date
Msg-id 50CB8913.8050202@dunslane.net
Whole thread Raw
In response to Re: backend suddenly becomes slow, then remains slow  (Tom Lane <tgl@sss.pgh.pa.us>)
Responses backend suddenly becomes slow, then remains slow  (Jeff Janes <jeff.janes@gmail.com>)
List pgsql-performance
On 12/14/2012 02:56 PM, Tom Lane wrote:
> Andrew Dunstan <andrew.dunstan@pgexperts.com> writes:
>> One of my clients has an odd problem. Every so often a backend will
>> suddenly become very slow. The odd thing is that once this has happened
>> it remains slowed down, for all subsequent queries. Zone reclaim is off.
>> There is no IO or CPU spike, no checkpoint issues or stats timeouts, no
>> other symptom that we can see. The problem was a lot worse that it is
>> now, but two steps have alleviated it mostly, but not completely: much
>> less aggressive autovacuuming and reducing the maximum lifetime of
>> backends in the connection pooler to 30 minutes.
>> It's got us rather puzzled. Has anyone seen anything like this?
> Maybe the kernel is auto-nice'ing the process once it's accumulated X
> amount of CPU time?
>
>


That was my initial thought, but the client said not. We'll check again.

cheers

andrew



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