[pgpool-hackers: 1293] Re: pgpool zombie with wathdog 3.5

Yugo Nagata nagata at sraoss.co.jp
Mon Jan 4 14:16:58 JST 2016


Hi Usama,

On Tue, 29 Dec 2015 03:32:00 +0500
Muhammad Usama <m.usama at gmail.com> wrote:

> Hi Yugo
> 
> Many thanks for the patch. Although the patch takes care of zombie
> processes, but I think blocking the watchdog process at time of escalation
> and de-escalation might lead to some un-expected results, because at that
> time when the watchdog process will be waiting for the
> escalation/de-escalation process to finish it would not be replying to
> other nodes.
> So can you please have a look at the attached path which uses the SIGCHILD
> to handle the zombie process problem

I have looked at and tested this and I think this is good to be committed.

> 
> Thanks
> Best regards
> Muhammad Usama
> 
> On Mon, Dec 28, 2015 at 2:11 PM, Yugo Nagata <nagata at sraoss.co.jp> wrote:
> 
> > Hi Usama,
> >
> > I write the patch to fix it.
> >
> > In current, escalation process is forked but not waited by watchdog
> > process. Fix is to wait the escalation process by waitpid. That is,
> > watchdog is blocked while waiting the escalation finishing.
> >
> > Any comment?
> >
> > Regards,
> >
> > On Mon, 21 Dec 2015 16:46:33 +0900
> > Yugo Nagata <nagata at sraoss.co.jp> wrote:
> >
> > > Usama,
> > >
> > > A zombie process appeared after pgpool started with watchdog.
> > >
> > > $ ps aux | grep pgpool
> > > ...
> > > yugo-n   32156  0.0  0.0  19880  1244 pts/27   S    16:31   0:00 pgpool:
> > watchdog
> > > yugo-n   32165  0.0  0.0      0     0 pts/27   Z    16:31   0:00
> > [pgpool] <defunct>
> > > yugo-n   32166  0.0  0.0  17792   768 pts/27   S    16:31   0:00 pgpool:
> > lifecheck
> > > ...
> > >
> > > I found PID 32165 was pid of the escalation process.
> > >
> > >  2015-12-21 16:31:33: pid 32156: LOG:  escalation process started with
> > PID:32165
> > >  2015-12-21 16:31:33: pid 32165: LOG:  watchdog: escalation started
> > >
> > > I can reproduce this on Ubuntu but not CentOS.
> > >
> > > Regarads,
> > > --
> > > Yugo Nagata <nagata at sraoss.co.jp>
> > > _______________________________________________
> > > pgpool-hackers mailing list
> > > pgpool-hackers at pgpool.net
> > > http://www.pgpool.net/mailman/listinfo/pgpool-hackers
> >
> >
> > --
> > Yugo Nagata <nagata at sraoss.co.jp>
> >
> > _______________________________________________
> > pgpool-hackers mailing list
> > pgpool-hackers at pgpool.net
> > http://www.pgpool.net/mailman/listinfo/pgpool-hackers
> >
> >


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


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