[pgpool-general: 1705] Re: poor performance w/ pgpool

Kyle O'Donnell kyleo at 0b10.mx
Thu May 9 08:40:12 JST 2013


Thanks for the info.

There are 8 cores available per server and most of them are idle (only about 3 cores were active at ~30% CPU) so I don't think that's an issue.

We are using all 10GB network and not generating near that amount of traffic (~40mb/sec at peak)

The disks are all SAN (stripped across 2x5disk raid5s with 4GB of write cache) and there is less than 1ms io wait on average.

SSL is enabled.  I'll try to disable that and let you know the results.

-Kyle

----- Original Message -----
From: "Tatsuo Ishii" <ishii at postgresql.org>
To: kyleo at 0b10.mx
Cc: pgpool-general at pgpool.net
Sent: Wednesday, May 8, 2013 7:10:37 PM
Subject: Re: [pgpool-general: 1701] poor performance w/ pgpool

> I haven't had a chance to put any performance monitoring in place but I can say for certain that my application is unable to keep up with our expected load when I use pgpool.  If I point the application directly to postgres we are able to process the expected load. 
> 
> Here is the setup
> 
> node1
> primary pgpool
> primary postgres
> 
> node2
> backup pgpool
> async streaming replication postgres
> 
> num_init_children = 100
> max_pool = 9 
> postgres max set to 1000
> 
> (load balance mode turned off, watchdog enabled)
> 
> client (jdbc) is doing 100% writes 0% reads its doing ~1000 inserts per second.
> 
> I am going to start putting in more monitoring right now, but has anyone else seen this?  Are there tweaks to pgpool I should be making?

Pgpool does nothing good for this type of load. It just gives an
overhead to read packets from clients and foward to PostgreSQL, and
vice versa.

However there are something to mitigate the overhead:

- Do not use SSL. To process SSL connections, pgpool needs to work hard.

- Give pgpool enough CPU resource. In your configuration pgpool has to
  share CPU resource with PostgreSQL. Adding CPU core might be a good
  idea.

- Use high speed network device.
--
Tatsuo Ishii
SRA OSS, Inc. Japan
English: http://www.sraoss.co.jp/index_en.php
Japanese: http://www.sraoss.co.jp


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