Re: Re: [bug fix] Cascading standby cannot catch up and get stuck emitting the same message repeatedly

On Mon, Sep 5, 2016 at 8:42 AM, Tsunakawa, Takayuki
<tsunakawa(dot)takay(at)jp(dot)fujitsu(dot)com> wrote:
>
> From: pgsql-hackers-owner(at)postgresql(dot)org
> > [mailto:pgsql-hackers-owner(at)postgresql(dot)org] On Behalf Of Tsunakawa,
> > Our customer hit a problem of cascading replication, and we found the cause.
> > They are using the latest PostgreSQL 9.2.18. The bug seems to have been
> > fixed in 9.4 and higher during the big modification of xlog.c, but it's
> > not reflected in older releases.
> >
> > The attached patch is for 9.2.18. This just borrows the idea from 9.4 and
> > higher.
> >
> > But we haven't been able to reproduce the problem. Could you review the
> > patch and help to test it? I would very much appreciate it if you could
> > figure out how to reproduce the problem easily.
>
> We could successfully reproduce the problem and confirm that the patch fixes it. Please use the attached script to reproduce the problem.
>

I have tried using attached script multiple times on latest 9.2 code,
but couldn't reproduce the issue. Please find the log attached with
this mail. Apart from log file, below prints appear:

WARNING: enabling "trust" authentication for local connections
You can change this by editing pg_hba.conf or using the option -A, or
--auth-local and --auth-host, the next time you run initdb.
20075/20075 kB (100%), 1/1 tablespace
NOTICE: pg_stop_backup complete, all required WAL segments have been archived
20079/20079 kB (100%), 1/1 tablespace

Let me know, if some parameters need to be tweaked to reproduce the issue?

It seems that the patch proposed is good, but it is better if somebody
other than you can reproduce the issue and verify if the patch fixes
the same.

--
With Regards,
Amit Kapila.
EnterpriseDB: http://www.enterprisedb.com