[pgpool-general: 9244] pgpool connection timeout

[Ang Sei Heng]

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.

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.

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


Regards,
Sei Heng






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