[pgpool-general: 1649] Re: inserts sent to standby

[Michael Betts]

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
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
>>