[pgpool-general: 740] Re: pgpool causes high load

[Tatsuo Ishii]

My guess is this:
http://git.postgresql.org/gitweb/?p=pgpool2.git;a=commit;h=8ffb7f63664ff9c7d4682ac58842abf187f0892d

The part which handles incoming events has been changed when 3.1 was
released. Since then we have had several reports including near
infinite loop which consumes CPU a lot. Though the problem reported in
above is not similar to yours, I suspect the previous code could cause
your problem. Can you try patch (can be downloaded from "patch" link
or the latest snapshot of 3.1-stable tree?  (can be downloaded from
http://git.postgresql.org/gitweb/?p=pgpool2.git;a=shortlog;h=refs/heads/V3_1_STABLE)
--
Tatsuo Ishii
SRA OSS, Inc. Japan
English: http://www.sraoss.co.jp/index_en.php
Japanese: http://www.sraoss.co.jp

> Dear list members,
> 
> since we have updated our pgpools to the latest stable version (3.1.3), we have regular peaks of high load on our machines. Every 5 to 10 minutes the server load (average 1 min load) raises up to 50, but then recovers within the next minutes to normal values again. CPU usage and IO wait are unaffected and show normal values during the whole time, so we cannot identify the processes that cause the load. Do you have any ideas what might cause this behavior? We didn't have that problems with the previous version of pgpool (3.0.4).
> 
> We suspected the root of the problem in child_life_time, which was set to 300. Thus we increased that value up to 7200 (2 hours), however it didn't improve the situation at all. Another measure was adjusting child_max_connections from 1500 to 1000 which also didn't solve the issue. Max_pool is set to 1.
> 
> Our pgpools are running in master/slave mode and postgres streaming replication (2 postgres 9.1 backends).
> I want to add, that this problem is not that intense in another environment. However this environment does not have as many simultaneous connections (child_max_connections is set to 500),
> 
> Apart from that strange load problems everything works fine.
> 
> Regards,
> 
> petaFuel GmbH
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> IT Systemadministration
> 
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