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From Jeff Trawick <traw...@gmail.com>
Subject Re: [users@httpd] Prefork MPM: Locking of error logs during write?
Date Sun, 07 Sep 2014 23:30:35 GMT
On Sat, Sep 6, 2014 at 10:31 AM, Bill Moseley <moseley@hank.org> wrote:

> Apache 2.2.15 on Linux.
>
> When Apache children send output to stderr it ends up in my error_log file.
>
> Does Apache have any mechanism to prevent intermixing of this output?
> That is, if all Apache children write large ( but < 4k) strings to stderr
> does Apache have anything to prevent inter mixing of the output?
>
> Apache doesn't do any locking or use semaphores to prevent concurrent
> writing to the log, correct?
>
>
> --
> Bill Moseley
> moseley@hank.org
>

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.

-- 
Born in Roswell... married an alien...
http://emptyhammock.com/

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