Date: Tue, 11 Dec 2007 12:20:10 -0300
From: Alvaro Herrera <alvherre@alvh.no-ip.org>
To: Craig James <craig_james@emolecules.com>
Cc: pgsql-performance@postgresql.org
Subject: Re: libgcc double-free, backend won't die
Message-ID: <20071211152010.GE10710@alvh.no-ip.org>
References: <7EB0D6C0-48E2-4155-8559-9113D3BD2785@ketema.net>
	<4728CF7B.7040306@gmail.com> <4728FB3E.3070709@shaw.ca>
	<472978BE.9@hagander.net> <4729B1E9.2080306@gmail.com>
	<475E4133.5080009@emolecules.com>
	<20071211112128.GB4708@alvh.no-ip.org>
	<475EA754.1090307@emolecules.com>
	<20071211151416.GD10710@alvh.no-ip.org>
	<475EA9FD.9000706@emolecules.com>
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Craig James wrote:
> Alvaro Herrera wrote:
>> Craig James wrote:
>>
>>> Here is my guess -- and this is just a guess.  My functions use a
>>> third-party library which, of necessity, uses malloc/free in the
>>> ordinary way.  I suspect that there's a bug in the Postgres palloc()
>>> code that's walking over memory that regular malloc() allocates.  The
>>> third-party library (OpenBabel) has been tested pretty thoroughly by
>>> me an others and has no memory corruption problems.  All malloc's are
>>> freed properly.  Does that seem like a possibility?
>>
>> Not really.  palloc uses malloc underneath.
>
> But some Postgres code could be walking off the end of a malloc'ed
> block, even if palloc() is allocating and deallocating correctly.
> Which is why I was hoping to use valgrind to see what's going on.

I very much doubt it.  Since you've now shown that OpenBabel is
multithreaded, then that's a much more likely cause.

-- 
Alvaro Herrera                  http://www.amazon.com/gp/registry/5ZYLFMCVHXC
"When the proper man does nothing (wu-wei),
his thought is felt ten thousand miles." (Lao Tse)