Re: query log corrupted-looking entries

From: Alvaro Herrera <alvherre(at)commandprompt(dot)com>
To: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
Cc: George Pavlov <gpavlov(at)mynewplace(dot)com>, "Ed L(dot)" <pgsql(at)bluepolka(dot)net>, pgsql-general(at)postgresql(dot)org
Subject: Re: query log corrupted-looking entries
Date: 2007-06-08 01:32:01
Message-ID: 20070608013201.GD20828@alvh.no-ip.org
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Tom Lane wrote:
> "George Pavlov" <gpavlov(at)mynewplace(dot)com> writes:
> > I tried the patch and it has no effect whatsoever -- even with the
> > patch, under the correct load the corrupted entries are coming fast and
> > furious (I found a load profile on my app that reproduces these very
> > clearly).
>
> What are the total lengths of the log entries in which you see the
> failure? (The "length" here includes all the lines belonging to a
> single logical entry, eg, ERROR, DETAIL, HINT.)
>
> I believe that this shouldn't be happening except in the case in which
> the entry-interpolated-into exceeds PIPE_BUF bytes. I'm not entirely
> sure what PIPE_BUF is on Linux machines, but IIRC the Posix spec says it
> has to be at least 512, and on older Unix kernels it tends to be 8K.

4096, although for some archs it may be bigger (it's the page size).

--
Alvaro Herrera http://www.CommandPrompt.com/
The PostgreSQL Company - Command Prompt, Inc.

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