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Re: [GENERAL] (Never?) Kill Postmaster?

From: Christian Schröder <cs(at)deriva.de>
Date: Sun Nov 11 2007 - 15:49:07 EST

Tom Lane wrote:
>
>> I recompiled the server with debugging symbols enabled and then did the
>> following experiment: I started a query which I knew would take some
>> time. While the query executed I disconnected my dial-up line. After
>> reconnecting the backend process was still there (still SELECTing).
>> Meanwhile the query is finished and the process is idle, but it's still
>> present.
>>
>
> That is probably not the same situation because (assuming the query
> didn't produce a lot of output) the kernel does not yet think that the
> network connection is lost irretrievably. You'd have to wait for the
> TCP timeout interval to elapse, whereupon the kernel would report the
> connection lost (EPIPE or ECONNRESET error), whereupon we'd enter the
> code path shown above.
>

That's what I also thought, but unfortunately it doesn't seem to be the same situation. After a while, the connection disappears and the server log says (quite correct in my opinion):

<2007-11-11 18:45:43 CET - chschroe> LOG: could not receive data from client: Die Wartezeit für die Verbindung ist abgelaufen <2007-11-11 18:45:43 CET - chschroe> LOG: unexpected EOF on client connection

> One thing I'm suddenly thinking might be related: didn't you mention
> that you have some process that goes around and SIGINT's backends that
> it thinks are running too long? I'm wondering if a SIGINT event is a
> necessary component of producing the problem ...
>

Maybe. On the other hand, I sent a SIGINT to my process and it nonetheless didn't show the strange behaviour. To test this I will change the script so that it will leave alone the processes of one of the users.

I think the users will create some more unkillable processes tomorrow. As soon as I have some, I will send you the login data for the server so that you can have a look for yourself.

Regards,

Christian

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Received on Sun Nov 11 15:50:16 2007

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