[pgpool-general: 5221] Re: ERROR: unable to read data from frontend

[Avi Weinberg]

Hi experts,

Will it be more likely to get this error if we have connection_cache = off or when we have connection_cache = on

How can we gracefully close all connections to pgpool when we bring down tomcat?

Should client_idle_limit=60 be reasonable?

Thanks
Avi

-----Original Message-----
From: pgpool-general-bounces at pgpool.net [mailto:pgpool-general-bounces at pgpool.net] On Behalf Of Tatsuo Ishii
Sent: Tuesday, January 10, 2017 2:34 AM
To: rolan3 at gmail.com
Cc: pgpool-general at pgpool.net
Subject: [pgpool-general: 5220] Re: ERROR: unable to read data from frontend

> Hi,
>
> we are encountering an issue in our labs in which some pgpool
> connections are stuck until reboot to the machine or the pgpool service.
>
> this issue has occurred at least 4 times so far in our labs in 3
> different setups.
>
> this is from the logs (the same lines several times):
> ..
>
> *2017-01-05 22:35:18: pid 1729: ERROR:  unable to read data from
> frontend2017-01-05 22:35:18: pid 1729: DETAIL:  EOF encountered with
> frontend*
> ...
>
> another occurrence (the same lines several times):
> ...
>
>
> *2017-01-05 22:18:47: pid 11860: DETAIL:  EOF encountered with
> frontend*
>
>
> *2017-01-05 22:18:47: pid 21006: ERROR:  unable to read data from
> frontend*
>
> *2017-01-05 22:18:47: pid 21006: DETAIL:  EOF encountered with
> frontend*

Probably these are not related to the stuck problem.

> *2017-01-05 22:18:47: pid 14895: LOG:  failback event detected*
> * 2017-01-05 22:18:47: pid 14895: DETAIL:  restarting myself* ...
>
> In our labs pgpool and postgres is running on the same machine.
>
> after this issue occurred, although we brought down the application,
> we could see processes in the following state: "pgpool: idle in transaction"
> (until we restarted pgpool)

Have you enabled client_idle_limit in pgpool.conf?

I suspect "pgpool: idle in transaction" is caused by lazy clients which do not close transactions or connections. By setting client_idle_limit to non 0, Pgpool-II could kick out such that clients and keep child process can accept new connections from clients.

> pgpool version: 3.6.1
> PostgreSQL version: 9.5.4
> OS: CentOS 6.5
>
> Thanks in advance,
> Rolan.

Best regards,
--
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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