[Pgpool-hackers] [Pgpool-committers] pgpool - pgpool-II: Fix child process crashes by accessing illegal

[Toshihiro Kitagawa]

On Mon, 31 Oct 2011 11:44:27 +0900 (JST)
Tatsuo Ishii <ishii at sraoss.co.jp> wrote:

> Toshihiro,
> 
> I think you need to explain why you committed this.
> 
> It seems you patches just postpone the problem we currently have.

Yes, this is the temporary fix until we fix a fundamental problem
which causes segfault at memory context.

> In your patches if we have problem with pool_memory_free(), you just do nothing and instead do:
> 
>    pool_debug("An adress \"%p\" does not exist in memory pool.", chunk);
> 
> Because this is just a debug statement and debug mode never turned on
> in the production environment, I think this makes things even
> worse. Because the patches silently ignore the problem currently we
> have, it is possible that we later on have even worse problem.
> 
> I think at least we should change above to pool_error().

This fix is based on the core file which a user offered.

I could not reproduce the problem and find the location which cause
the breakage of memory context. However the user said it reappears
by all means when I operate application with a certain hardware.

I am concerned about this fix having possibilities to emit a large
quantity of error logs by an unknown certain operation.

-- 
Toshihiro Kitagawa
SRA OSS, Inc. Japan

> --
> Tatsuo Ishii
> SRA OSS, Inc. Japan
> English: http://www.sraoss.co.jp/index_en.php
> Japanese: http://www.sraoss.co.jp
> 
> From: kitagawa at pgfoundry.org (User Kitagawa)
> Subject: [Pgpool-committers] pgpool - pgpool-II: Fix child process crashes by accessing illegal
> Date: Mon, 31 Oct 2011 02:35:33 +0000 (UTC)
> Message-ID: <20111031023533.702FA532C80E at pgfoundry.org>
> 
> > Log Message:
> > -----------
> > Fix child process crashes by accessing illegal memory context.
> > 
> > Tags:
> > ----
> > V3_0_STABLE
> > 
> > Modified Files:
> > --------------
> >     pgpool-II/parser:
> >         pool_memory.c (r1.10 -> r1.10.8.1)
> >         (http://cvs.pgfoundry.org/cgi-bin/cvsweb.cgi/pgpool/pgpool-II/parser/pool_memory.c?r1=1.10&r2=1.10.8.1)
> > _______________________________________________
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>