[pgpool-general: 9246] Re: pgpool connection timeout

[Ang Sei Heng]

 From what we found, the problem is very likely pgpool.

When we try to run psql -p <pgpool port>, it just hanged without 
response. We were able to run psql  -p <postgres port>.

Everything resume normal after we restarted pgpool, while no other task 
was restarted.

On 10/29/24 6:23 PM, Tatsuo Ishii wrote:
>> 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
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