[pgpool-general: 9245] Re: pgpool connection timeout

[Tatsuo Ishii]

> Hello,
> 
> Recently our pgpool setup encountered an unexpected performance issue.
> 
> What has happened is as follow:
> 
> 1) There is an application that will make a DB connection via pgpool
> to insert new record into a table.
> 2) Once the record inserted, the task will close the connection and
> wait for the next request.
> 3) There was a sudden surge in the total records need to be inserted
> into the system.
> 4) The task halted its processing as it is unable to make new DB
> connection after it closed the previous connection.
> 5) All other task that also making DB connection also encountered
> connection timeout or DB non responding error.
> 6) psql console was not able to establish as well.

It seems #3 is totally unrelated to pgpool because the application
does not connect at that point. I am puzzled too.

> The issue was resolved after we restart pgpool. There was no restart
> needed of postgresql.
> 
> There was no error found in pgpool's log, it just has no new
> connection came in.  We came to conclude, it seems the available pool
> has been used up.

When the incident happens, can you share the output of pcp_proc_info -a?

> Our end was very puzzled by this incident, since our task does close
> the connection before making the next DB call, so how could the pool
> be used up when our task will always release/disconnect before making
> new connection? Is there any configuration we need to set in pgpool to
> better optimise it?
> 
> The version we are using:
> 
> - pgpool-II version 4.5.1 (hotooriboshi)
> - psql (PostgreSQL) 15.6

Is there any non-default setting in pgpool.conf?

Best reagards,
--
Tatsuo Ishii
SRA OSS K.K.
English: http://www.sraoss.co.jp/index_en/
Japanese:http://www.sraoss.co.jp