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From "Bill Stoddard" <>
Subject Re: Apache 2.0.28 memory growth issue.
Date Fri, 11 Jan 2002 18:27:42 GMT

> Aaron Bannert wrote:
> > Keep in mind that the multithreaded MPMs will by their very nature have
> > higher memory requirements than their single-threaded counterparts. I
> > regularly see memory usage in the range you've reported. Yesterday
> > while running with 500 threads, I can report that httpd was using 23M
> > (20M RSS).  If you consider that 500 prefork processes would take on
> > the order 500*N, where N is usually 3-5MB, then this is a *significant*
> > decrease in memory requirements -- which was one of the major goals of
> > the hybrid multiprocess/ multithreaded httpd model.
> Good point.  I can see it while worker is getting pounded.
> hmmmn, but what if the traffic dries up completely?  Should we expect memory
> usage to shrink back down close to where it started?
> Greg

Depends on the implementation details of the worker MPM. Specifically, do you preallocate
a ptrans pool for each and every worker thread or allocate one only when the thread is
dispatched to handle a request? Once a ptrans pool is allocated, do you free it when the
thread goes back into the worker pool?


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