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From Bill Moseley <>
Subject Re: [users@httpd] Prefork MPM: Locking of error logs during write?
Date Mon, 08 Sep 2014 03:34:36 GMT
On Sun, Sep 7, 2014 at 4:30 PM, Jeff Trawick <> wrote:

> Apache httpd on Unix doesn't use locking.  The file is opened in the
> parent with O_APPEND.
> If the writers inherit that descriptor, all is okay for "small" buffers;
> if a writer opens without O_APPEND, bad.

Thanks Jeff,

In my tests over the last few days it's clear that buffer is about 4K (On
CentOS, anyway).   I wrote tens of gigs of logs using 50 processes and
never say any intermixing of the logs at all with the message < 4K.   With
a larger log message it was easy to trigger the mixing of logs.

Thanks for the information and confirmation.

Bill Moseley

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