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Re: libpq, threads and connection reset

From: Joe Murphy <joe(dot)murphy(at)aersoft(dot)ie>
To: "pgsql-interfaces(at)postgresql(dot)org" <pgsql-interfaces(at)postgresql(dot)org>
Subject: Re: libpq, threads and connection reset
Date: 2002-09-05 12:54:59
Message-ID: 3D775423.78A43764@aersoft.com (view raw or flat)
Thread:
Lists: pgsql-interfaces
Sorry, a typo in my previous message see below....

Joe Murphy wrote:

> I'm having some problems with a multi-threaded application using libpq:
>
> Some details:
> OS: Solaris 2.6
> Postgres version 7.2.1
>
> When my application starts up the main thread (1) connects using
> PQsetdbLogin() which is successful
> Another thread (5 for example) issues queries over this connection.
>
> My test is stopping postgres (KILL -INT) and testing if my application
> detects the backend failure and
> tries to re-connect.
>
> Thread 5 issues a PQexec and discovers the error upon which thread 5
> tries to reconnect (after calling PQfinish)
> This reconnection HANGS, here is a stack trace:
>
>      ee037438 poll     (ed906e48, 1, ffffffff)
>      ee04cc74 select   (ed906e50, ed908ea8, ed908f28, ed908eac,
> ed908f2c, 4) + 280
>      ee69e010 pqWait   (0, 1, 485e8, 1, 81010100, ee0882cc) + 1d8
>      ee695178 connectDBComplete (485e8, 0, ee0a3180, 0, efffebc0,
> ee086858) + f8
>      ee69484c PQsetdbLogin (45e28, ed9091a2, 0, 0, 45d68, 45e40) + 558
>
> All access using the connection is serialized using a mutex.
>
> I've tried the same test but with everything running in thread 1 and it
> works OK.
>
> I've managed to spot some differences between the two tests:
>
> Multi Threaded test:

This should read "Single Threaded Test"

>
> The re-connect underlying call to connect returns -1 and sets errno to
> 146 (connection refused)
>
> Single Threaded test:

This should read Multi Threaded test

>
> The re-connect underlying call to connect returns -1 and errno = 0, so
> it thinks the connection is "in progress" and tries
> to complete the connection - but hangs on the select (poll)
>
> Any help or ideas greatly appreciated,
>
> Joe
>
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--
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                        Joe Murphy - AerSoft Limited
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