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From: system@niuhep.physics.niu.edu
Subject: Too many tasks?  overhead questions.
Date: 1997/04/23
Message-ID: <5jlkdu$rub@corn.cso.niu.edu>#1/1
X-Deja-AN: 236905539
Organization: N.Ill.U. Physics Dept.
Reply-To: system at physics.niu.edu.nospam
Newsgroups: comp.lang.ada
Date: 1997-04-23T00:00:00+00:00
List-Id: <comp.lang.ada>


Hello,
Largely as a learning exercize I am writing*  a mud** with Ada using the
Gnat compiler.  One of the possibilities is to make it highly threaded 
with each character getting their own thread. (Yes, there are design 
reasons for doing this)

However, assuming that I ever complete this project the mud may actually
run for extended periods of time on a non-dedicated machine.

The result of this is that I would have between a few hundred and potentially
a few thousand tasks running around.  The tasks would exist for significant
periods of time (hours) and interact with the world and each other.
(My minimal digging in this area suggests that I would be using ?protected
functions? to deal with synchonization issues)

My question is what kind of overhead would this entail.  There are
three probable operating environments: Digital Unix on an Alpha probably
with 128 mb but possibly 64, OS/2 on a pentium 133 with 32mb, VMS on
an Alpha with at least 128mb.

Muds are not generally cpu intensive (but then they don't generally
have a few hundred threads) so I am mostly concerned about memory
and ??? I don't know what else.

If I ran it on the OS/2 machine it may well only have a hundred or
even fewer tasks.

Out of curiousity I am wondering how tasks are going to be handled
by the VMS compiler.  Presumably not by using full-fledged processes.
Dec-Threads, perhaps?

I am not looking for hard and fast numbers (rather obviously) just
some general ideas of what to expect if I go this route.

Robert

*Well, I have written some code, but truthfully I am mostly still in the 
design mode.
**For those who have a real life a mud is a computer game in which
multiple people interact with each other and the world described by the
game.

specify the e-mail address below, my reply-to: has anti-spam added to it
Morphis@physics.niu.edu
Real Men change diapers