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Date: Sat, 14 Mar 2009 08:40:22 +0900
Message-ID: <6456355d0903131640w19d173adl1d58b14ae888157a@mail.gmail.com>
Subject: Re: custom background thread and module sharing a data structure
From: Andrej van der Zee <andrejvanderzee@gmail.com>
To: modules-dev@httpd.apache.org
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Hi,


> My point is that within a single process, multiple threads can service
> requests that can end up firing your module code. If you only do process
> locking you can still have more than 1 thread executing your module code at
> the same time.
>
> Just a process level lock will *not* guarantee that only a single thread is
> executing your code within the process holding the lock. A inter thread lock
> is needed to synchronize multiple threads within that processes from
> stomping on a shared resource.
>
>
Yeah you are right, two thread in the same process in the mpm worker model
still execute the same code to access the shared inter-process resource. So
I guess I need to add the thread-based mutexes within a APR_HAS_THREADS
define, like in some other modules I have seen. Thanks for clearing this up!

Cheers,
Andrej

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