[pgpool-general: 1650] Re: inserts sent to standby

[Tatsuo Ishii]

> Tatsuo,
> 
> I did this but don't have enough information as rsyslogd is dropping messages due to rate limiting.  I will try and reproduce this problem in a test environment.
> 
> Meanwhile, I turned delay_threshold off and debug off and restarted pgpool. I no longer see inserts being sent to the standby, however, I encountered another problem which is that pgpool becomes unresponsive and clients can't connect.  The cpu usage spikes to 100%.  Right before this happened, I see this in the log file:
> 
> Apr 20 08:01:07 ip-10-140-76-210 pgpool[2133]: pool_process_query: discard E packet from backend 1

This means pgpool receives certain error message from backend 1. Can
you find an error around this time in PostgreSQL log?

> Apr 20 08:01:07 ip-10-140-76-210 pgpool[2133]: pool_read: EOF encountered with backend
> Apr 20 08:01:07 ip-10-140-76-210 pgpool[2133]: pool_read: EOF encountered with backend
> Apr 20 08:01:07 ip-10-140-76-210 pgpool[2133]: detect_stop_postmaster_error: detect_error error
> Apr 20 08:01:07 ip-10-140-76-210 pgpool[2133]: detect_postmaster_down_error returns error on backend 1. Going to close this session.
> 
> To me it looks like there was a communication error with the standby. Is this what this means? Show pool_nodes shows both nodes with status of 2 after this. Shouldn't show pool_nodes show the standby with a status of 3 after this? And does pgpool recover from this or do I need to restart?
> 
> Thanks again for your great product and assistance,
> 
> Mike
> 
> 
> On Apr 18, 2013, at 6:49 PM, Tatsuo Ishii wrote:
> 
>> I had hard times to reproduce your problem. Can you change pgpool.conf
>> (debug = 1) and do pgpool reload, then send an insert to pgpool? That
>> should produce detailed debug information.
>> --
>> Tatsuo Ishii
>> SRA OSS, Inc. Japan
>> English: http://www.sraoss.co.jp/index_en.php
>> Japanese: http://www.sraoss.co.jp
>> 
>>> Tatsuo,
>>> 
>>> Thank you for confirming this.  I have experienced the same behavior again.  Is there something I can do to help provide information about this problem?
>>> 
>>> Thanks,
>>> 
>>> Mike
>>> 
>>> On Apr 16, 2013, at 7:41 PM, Tatsuo Ishii wrote:
>>> 
>>>>> I have been running pgpool 3.2.3 in production and everything has been working great.  However, I recently had an incident where pgpool started sending inserts to the the read-only standby and not the master.  I'm using master/slave mode with streaming replication and both the master and slave were up and running and when I checked the pgpool status, everything seemed normal.  I'm also using delay_threshold = 100000.  When this incident occurred, it was after a large data update in which the lag exceed this threshold.  I believe that once the threshold was no longer exceeded, it started sending queries back to the standby and also started sending inserts there too.
>>>>> 
>>>>> Am I understanding this feature correctly?  If the lag exceeds the delay_threshold, it stops sending queries to the standby and when it drops below the threshold, it resumes.  Any idea as to why it would send inserts to the standby?  I did not have debug on, so I don't have much information to go on, except I do know that the delay_threshold was exceeded and shortly after it was no longer exceeded, this started happening.  Restarting pgpool cleared it up.
>>>> 
>>>> Your understanding of delay_threshold behavior is correct and sounds
>>>> like the incident you observed is a bug. I will try to reproduce the
>>>> problem to find out what is wrong.
>>>> --
>>>> Tatsuo Ishii
>>>> SRA OSS, Inc. Japan
>>>> English: http://www.sraoss.co.jp/index_en.php
>>>> Japanese: http://www.sraoss.co.jp
>>> 
>