[pgpool-general: 4676] Re: ERROR: unable to read data from frontend

[Yugo Nagata]

I don't know the exact reason, but I think this is a problem at the
application side or the connection between the app and pgpool because
there are no doubt that pgpool received EOF from the application.

On Tue, 10 May 2016 17:56:39 +0000
Wolf Schwurack <wolf at uen.org> wrote:

> I have been trying to reproduce the error but unable too. When I tail pgpool.log file I notice the errors but not sure how it happens. The error shows that it come from one of our applications which has about 100 connections to pgpool. We have other applications also connected, around 700 connections to pgpool 
> 
> Wolf 
> 
> -----Original Message-----
> From: Yugo Nagata [mailto:nagata at sraoss.co.jp] 
> Sent: Tuesday, May 10, 2016 3:03 AM
> To: Wolf Schwurack <wolf at uen.org>
> Cc: 'pgpool-general at pgpool.net' <pgpool-general at pgpool.net>
> Subject: Re: [pgpool-general: 4662] ERROR: unable to read data from frontend
> Importance: High
> 
> Wolf,
> 
> Though some "ERROR: unable to read data from frontend" problems are fixed[1][2], pgpool still emits this error message when it receives EOF from the frontend.
> For example, I can reproduce this error by `kill -9` psql which is connecting to pgpool. This is expected behavior.
> 
> [1] http://git.postgresql.org/gitweb/?p=pgpool2.git;a=commit;h=d5cd159001d6616d8b12346f80831db026ad4b7c
> [2] http://git.postgresql.org/gitweb/?p=pgpool2.git;a=commit;h=c0ed0aac08631786116169c4ffac7fe19f3667b0
> 
> What does your application when the error occurs? If it isn't the application problem, could you tell me how to reproduce this error in your environment?
> 
> On Mon, 9 May 2016 15:34:24 +0000
> Wolf Schwurack <wolf at uen.org> wrote:
> 
> > Yugo
> > 
> > I tried to send the pgpool.log file but it exceeds the size limits 
> > Here is a few lines from pgpool.log
> > 2016-04-21 14:33:47: pid 19648: ERROR:  unable to read data from 
> > frontend
> > 2016-04-21 14:33:47: pid 19648: DETAIL:  EOF encountered with frontend
> > 2016-04-21 14:33:47: pid 19764: ERROR:  unable to read data from 
> > frontend
> > 2016-04-21 14:33:47: pid 19764: DETAIL:  EOF encountered with frontend
> > 
> > 
> > We are using simple protocol and memory query cache is set to off.
> > 
> > Wolf
> > 
> > 
> > -----Original Message-----
> > From: Yugo Nagata [mailto:nagata at sraoss.co.jp]
> > Sent: Sunday, May 08, 2016 9:23 PM
> > To: Wolf Schwurack <wolf at uen.org>
> > Cc: 'pgpool-general at pgpool.net' <pgpool-general at pgpool.net>
> > Subject: Re: [pgpool-general: 4662] ERROR: unable to read data from 
> > frontend
> > Importance: High
> > 
> > On Thu, 5 May 2016 13:17:05 +0000
> > Wolf Schwurack <wolf at uen.org> wrote:
> > 
> > > We been getting this error "ERROR: unable to read data from frontend" I did a search on the error it shows that it was bug in version 3.4.0 but that it's been fixed.
> > > 
> > > We are on version pgpool II version 3.4.4 Should the fix be in this version? When the error happens we are getting TIME_WAIT on the application server. We had up to 170 TIME_WAIT's in a minute's time.
> > > 
> > > We have two pgpool servers and two PostgreSQL servers running 
> > > streaming replication
> > > 
> > > Servers: Ubuntu 14.04.4
> > > PostgreSQL: 9.5.2
> > > Pgpool: 3.4.4
> > 
> > Do you use extended protocol (JDBC) or simple protocol? 
> > And, do you use in-memory query cache?
> > 
> > If possible, could you please provide pgpool log file.
> > 
> > > 
> > > 
> > > Wolfgang Schwurack
> > > Database/System Administrator
> > > Utah Education Network
> > > 801-587-9444
> > > wolf at uen.org
> > > 
> > > 
> > > 
> > 
> > 
> > --
> > Yugo Nagata <nagata at sraoss.co.jp>
> 
> 
> -- 
> Yugo Nagata <nagata at sraoss.co.jp>


-- 
Yugo Nagata <nagata at sraoss.co.jp>