[Pgpool-general] replication stability under heavy loads, many connections?

[Tatsuo Ishii]

Hi,

I am a pgpool-II developer but am not familiar with network staffs. Is
there anyone who can answer his questions?
--
Tatsuo Ishii
SRA OSS, Inc. Japan
English: http://www.sraoss.co.jp/index_en.php
Japanese: http://www.sraoss.co.jp

> Hello,
> What are suggested configurations for 
> num_init_children
> max_pool
> for heavy replication mode loads?
> we have 10 webservers connected to pgpool2.3.4-unreleased_cvs to two
> backends pg 8.3, all Debian Lenny virtual machines over XenServer 5.6.
> We may configure ram and cpu up to 32 Gb and 16  true cores "if needed",
> but currently using 4 GB and 8 cores to the pgpool Debian Lenny VM.
> The pg backends were tuned at another Debian Lenny VMs (at other
> physical Xen servers) and cope with the load.
> The php app is not well behaved, and it is not tolerant to almost any pg
> latencies. 
> Its profile is 95% selects and 5% inserts/updates.
> So we started with thousands connections (with kernel adjustments) and
> max pool left 4, then 3, then 2, then 1.
> Also reduced children reuses
> We also reconfigured tcp_tw_reuse kernel to 1 and abandoned tw recycle
> for network speed.
> 
> After reducing to 1k children, it worked for a week with low latency.
> When pgpool crashes it locks processes needing a killall to zap them.
> 
> What are recommended confs for high replication loads, low latency?
> Should we go the opposite, increase max pool and reduce init children?
> the php web app concurrently connects as the same db user.
> suggestions?
> Regards.
> Andre Felipe
> 
> 
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