[pgpool-general: 8362] Re: Active connection

j. e. j.emerlik at gmail.com
Tue Aug 23 16:47:03 JST 2022



Wysłane z iPhone'a

> Wiadomość napisana przez Bo Peng <pengbo at sraoss.co.jp> w dniu 23.08.2022, o godz. 06:59:
> 
> Hello,
> 
>> Hi,
>> I am using pgoool version 4.2.5 and  noticed somerhing disturbing.
>> 
>> pg_stat_statements showed one query in active state for long time, then I checked  network connecrions between pgpool and postgresql using netstat and connection between pgpool and frontend.
>> 
>> Connection between pgpool and postgresql is established but between pgpool and frontend is missed. 
>> 
>> command on pgpool:
>> 
>> ps aux showed IP and port of „connected„ frontend but connection in netstat is missed.
>> 
>> Why and what could have happened ?
>> How I can diagnose that ?
> 
> Your question is why the established connections was remained even there aren't any clients?
> This behavior is due to connection pooling feature.
> 
> You can disable this feature using:
> 
>    connection_cache = off
> 
> -- 
> Bo Peng <pengbo at sraoss.co.jp>
> SRA OSS LLC
> https://www.sraoss.co.jp/

 Connection cache is enabled in my configuration it’s a fact, but in my understanding, connection cache should work for connections with "idle" state with substring "DISCARD ALL" what means frontend is diskonected and pgpool cacheing this connection for some period of time (cached connection will be finished after time defined by child_life_time and I have it set to 60s).

In my case connection was in "active" state for few hours, client was disconeted and pgpool kept this connection, from postgresql point of  view it was wiat_event  ClientRead.

Something strange from my point of view.

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