Re: [HACKERS] Segmentation fault in libpq

From: Craig Ringer <craig(at)2ndquadrant(dot)com>
To: Andres Freund <andres(at)anarazel(dot)de>
Cc: Michal Novotný <michal(dot)novotny(at)greycortex(dot)com>, Merlin Moncure <mmoncure(at)gmail(dot)com>, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>, pgsql-bugs <pgsql-bugs(at)postgresql(dot)org>, PostgreSQL-development <pgsql-hackers(at)postgresql(dot)org>
Subject: Re: [HACKERS] Segmentation fault in libpq
Date: 2017-07-03 02:58:53
Message-ID: CAMsr+YF9jdu4TpX9F9WcwYqWSvp+4t20nwJNkOgqMfVVQ7TdsQ@mail.gmail.com
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On 3 July 2017 at 03:12, Andres Freund <andres(at)anarazel(dot)de> wrote:
> Hi,
>
> On 2017-07-02 20:58:52 +0200, Michal Novotný wrote:
>> thank you all for your advice. I've been investigating this a little more
>> and finally it turned out it's not a bug in libpq although I got confused
>> by going deep as several libpq functions. The bug was really on our side
>> after trying to use connection pointer after calling PQfinish(). The code
>> is pretty complex so it took some time to investigate however I would like
>> to apologize for "blaming" libpq instead of our code.
>
> Usually using a tool like valgrind is quite helpful to find issues like
> that, because it'll show you the call-stack accessing the memory and
> *also* the call-stack that lead to the memory being freed.

Yep, huge help.

BTW, on Windows, the free tool DrMemory (now 64-bit too, yay) or
commercial Purify work great.

--
Craig Ringer http://www.2ndQuadrant.com/
PostgreSQL Development, 24x7 Support, Training & Services

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