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Re: [PATCH] Adding callbacks to the core

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From:
Dave Mitchell
Date:
August 22, 2001 08:06
Subject:
Re: [PATCH] Adding callbacks to the core
Message ID:
200108221505.QAA11558@gizmo.fdgroup.co.uk
Nicholas Clark <nick@ccl4.org> wrote:
> [I don't understand threading, but I've read enough from Dan and Alan to
> learn that multi-CPU boxes will quite happily run different threads of
> the same process on the different CPUs at the same time, and this often
> does horrible things to code that was written without thinking about this]


IIRC, the main danger is that you cannot assume much about the visibility
of changes in shared memory between threads: just because thread A on
CPU 1 wrote to shared memory at location N chronologically before thread
B on on processor 2 tries to read it, doesnt mean that thread B will see the 
change - due to cache architectures etc. The pthreads book has some detailed
disussions on what you can and can't assume around mutexes, thread creation
etc etc.


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