R: BUG #6342: libpq blocks forever in "poll" function

From: "Andrea Grassi" <andreagrassi(at)sogeasoft(dot)com>
To: "'Craig Ringer'" <ringerc(at)ringerc(dot)id(dot)au>
Cc: <pgsql-bugs(at)postgresql(dot)org>
Subject: R: BUG #6342: libpq blocks forever in "poll" function
Date: 2011-12-16 14:10:47
Message-ID: 001201ccbbfc$82c987a0$885c96e0$@com
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The client program and the postgres server are on the same host, client connects to
In the meantime, my original program blocks (not my example but very probably the reasons are the same).

I typed "ps -C testprogramname -o wchan:80=" and the output was only a single dash ( "-" ).
I searched for the complete stack in /proc/$pid/stack (where $pid) was the pid of my process but this file doesn't exists !! Why ?

I'm waiting for my example to block in order to send you what you request me about the test program (even if the output almost surely will be the same).

Andrea Grassi

-----Messaggio originale-----
Da: Craig Ringer [mailto:ringerc(at)ringerc(dot)id(dot)au]
Inviato: venerdì 16 dicembre 2011 9.24
A: andreagrassi(at)sogeasoft(dot)com
Cc: pgsql-bugs(at)postgresql(dot)org
Oggetto: Re: [BUGS] BUG #6342: libpq blocks forever in "poll" function

On 12/16/2011 03:45 PM, andreagrassi(at)sogeasoft(dot)com wrote:
> The following bug has been logged on the website:
> Bug reference: 6342
> Logged by: Andrea Grassi
> Email address: andreagrassi(at)sogeasoft(dot)com
> PostgreSQL version: 8.4.8
> Operating system: SUSE SLES 10 SP4 64 BIT
> Description:
> Hi,
> I have a big and strange problem. Sometimes, libpq remains blocked in “poll”
> function even if the server has already answered to the query. If I attach
> to the process using kdbg I found this stack:
> __kernel_vsyscall()
> poll() from /lib/libc.so.6
Given all you described (thanks for all the detail!) then if client and
server are on different hosts this could easily be a NIC driver or HW
issue. It'd be interesting to see the output of:

ps -C testprogramname -o wchan:80=

Craig Ringer

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