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Subject Re: SYSV Semaphores.
Date Mon, 11 Dec 2000 14:22:54 GMT

There is another problem with SysV semaphores that needs to be seriously
considered.  If we kill ourselves off incorrectly, we will keep the
semaphore.  Also, anytime we choose a semaphore as a lock method, that is
all APR will use.  When APR is compiled as a shared library, this means
every APR program will use semaphores.  Since semaphores are usually
scarce, this is probably a bad idea.


> I'm looking into the use of SysV sems, for performance reasons. The
> reason we shut down on using them in 1.3 was the possibility of a
> denial-of-service using CGIs. However, after bothering Dean about it
> when he suggested their use on Linux, it appears that there are a
> couple of other ways to perform a denial of service using CGIs and the
> other locking methods, so the sems didn't look so bad, considering the
> performance boost they gave over flock. However, some measures seem to
> give conflicting results about the performance gain, so I am doing my
> own measurements now.
> Victor
> -- 
> Victor J. Orlikowski
> ======================

Ryan Bloom               
406 29th St.
San Francisco, CA 94131

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