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Date: Thu, 7 Oct 2004 15:27:19 -0400
From: Jeff Trawick <trawick@gmail.com>
Reply-To: Jeff Trawick <trawick@gmail.com>
To: dev@httpd.apache.org
Subject: Re: Bug: Apache hangs if script invokes fork/waitpid
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On Wed, 6 Oct 2004 11:01:23 -0700, Naik, Roshan <roshan.naik@hp.com> wrote:
> The Problem:
> ---------------
> I notice Apache 2(worker mpm) is not able to correctly handle
> a fork/waitpid invoked by a script used with mod_perl.

>From Ulrich Drepper: "No threaded programs must use anything but _exit
or exec after fork."
Perhaps a tiny bit harsh?

What if you fork a copy of a mutex used by some third-party Apache
module?  That module would need to be using pthread_atfork() to make
sure ownership is preserved properly.  Apache/APR certainly doesn't do
it with its mutexes.

I think there needs to be a mod_fork which provides a more general
purpose daemon than that used by mod_cgid, and some Apache API will
know whether or not to send a request over there.  This preserves the
goal of having fork() called only by single-threaded processes so that
all manner of pain is avoided.