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From "Bill Stoddard" <b...@wstoddard.com>
Subject Re: MPM re-write for network logic
Date Tue, 13 Nov 2001 04:20:13 GMT

>
> > On Monday 12 November 2001 07:22 pm, William A. Rowe, Jr. wrote:
> > > From: "Ryan Bloom" <rbb@covalent.net>
> > > Sent: Monday, November 12, 2001 8:55 PM
> > >
> > > > The problem that remains is Windows.  Windows starts the server, and
> > > > creates one thread for each socket that is configured.  That thread sits
> > > > in accept, and passes the accepted socket to worker threads.  This seems
> > > > like a waste of resources, but I will accept that the Windows experts
> > > > know what they are doing. My problem is that it doesn't really fit the
> > > > model above. I guess that Windows could work by using the first hook
> > > > above, and then looping through the apr_pollfd_t, creating threads that
> > > > call the third hook above.
> > >
> > > Uh... no, that's AcceptEx, and it has entirely different mechanics.  There
> > > will always be data to process when a winsock has accept-ex-ed a socket
> > > (thus the different API.)  Ergo, no thread is woken until it has a job to
> > > do.
> >
> > I have a stupid question.  I have been looking at the Windows code, and I
> > can't see where the data that is read by AcceptEx ever gets to the processing
> > thread.  Does that data ever get to the thread doing the work?  If so, how????
> >
>
> See PostQueuedCompletionStatus() and GetQueuedCompletionStatus().
>
> The worker thread pool blocks on GetQueuedCompletionStatus() in winnt_get_connection().
> winnt_accept() accepts connections and calls PostQueuedCompletionSTatus() to wake up
one
> of the workers blocked on GetQueuedCompletionStatus().
>
> Notice the queue of 'completion contexts' that flow between the two calls. And the
> ThreadDispatchIOCP is a Windows "Completion Port" a kernel resident FIFO queue of sorts.
>
> Give me a call tomorrow and I'll walk you through it in detail if you like.
>
> Bill
>

BTW, the NT code patch for accepting/dispatching connections is different from the Win9*
path. 9* does not support CompletionPorts.

Bill


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