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From Bill Stoddard <>
Subject Re: Thread/Process model discussion.
Date Fri, 29 Jan 1999 18:24:23 GMT
Rasmus Lerdorf wrote:
> > I have a question about the basic architecture you describe: Why are
> > you using both threads and processes? If threads by themselves aren't
> > good enough I'd take that as an indication that they probably
> > shouldn't be used on that platform.
> I like the hybrid process/thread architecture.  In a purely threaded
> environment a fatal error in a loaded module will take down your server.
> In the hybrid model only the requests served up by the threads in
> the process that died will be lost and further requests will be handled by
> threads in the other active processes.  It combines the robustness of the
> multi-process model with the performance and memory efficiency of the
> threaded model.

Rasmus makes the best argument for a hybrid process/thread architecture.
Another benefit is to overcome max threads per process limits in some
Unix variants. Earlier versions of AIX had a max thread per process
limit of 512 (this limit was removed in later versions of AIX). 
Bill Stoddard

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