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From "Brian Havard" <>
Subject Re: newbie thread/process model question in hybrid server
Date Sat, 10 Jul 1999 04:39:40 GMT
On Fri, 09 Jul 1999 14:07:40 -0400, Rodent of Unusual Size wrote:

>Brian Havard wrote:
>> Why is hybrid more scalable than purely threaded (with proper kernel
>> threads)? What advantage is there in dividing the threads between multiple
>> processes?
>A segfault won't take out 100% of your server's capacity,
>for one thing.

Yeah, fair point but this isn't a problem on OS/2 where I can trap segfaults
(and other fatal errors like div 0) and just kill the offending thread.

On Fri, 9 Jul 1999 13:14:24 -0500, Manoj Kasichainula wrote:

>Many (most?) systems limit the number of threads per process. In a
>thread-per-request model (which the hybrid server uses), if you want
>to handle 2000 concurrent requests but your threads/process = 512, you
>have to have multiple processes to handle the load.

Ok. Also not applicable to OS/2 which has no thread per process limit other
than the system limit which is user configurable (though needs a reboot to
change it).

On Fri, 09 Jul 1999 12:01:46 -0700, Vincent Janelle wrote:

>Also, some systems limit the max number of FDS per process to a tiny
>amount, and this doesn't get changed with a threaded process.  The
>entire webserver would only be able to handle up to `uname -n` open
>files across the system.  This means read(), etc..  The forked off
>processes would handle that AFAIK.

Ditto for file handles as for threads. Actually, OS/2 does impose a limit but
this can be set to any value (up to the system limit) by a single API call.

Well, I can see that the hybrid model makes sense on some platforms but I
don't believe OS/2 is one of them so I'll continue working on my single
process/multi-thread OS/2 mpm. This model may also be suitable for other
platforms like BeOS or Win32.

 |  Brian Havard                 |  "He is not the messiah!                   |
 |  |  He's a very naughty boy!" - Life of Brian |

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