[fpc-pascal]fork with forked program

Marco van de Voort marcov at stack.nl
Tue Sep 16 15:34:23 CEST 2003

> On dinsdag, sep 16, 2003, at 14:55 Europe/Brussels, Matt Emson wrote:
> > Got you. So the correct term would be 'multiprocess'. I always forget 
> > that
> > UNIX considers processes to be seperate to threads. BeOS does things
> > slightly differently. We have the notion of 'teams'. A thread belongs 
> > to a
> > 'team'. All threads are effectively light weight processes. However, 
> > and I
> > forget the exact reason, a team is not an exact equivilence to a UNIX
> > process.
> This has nothing to do with unix <-> BeOS. For example, Solaris is 
> definitely Unix and also uses the concept of light weight processes. 

Light weight processes are a Unix feature.

(heavy and cheap are relative to the other)
Windows -> heavy processes, cheap threads.  
Unix	-> cheap processes, expensive threads

Moreover Windows schedules threads, doesn't even treat processes
differently. Traditional unix didn't do this either, but several modern
OSes (like FreeBSD 5 (KSE)) can. 

> Different OS'es simply use different process models.

The differences are classic, but just like many other points in the
traditional unix vs mach kernel discussion, things are getting more blurred
because of cross-pollination. (think messaging, kernel loadable modules,
"special" kernel related servers in unix, moving of systems in kernel on
mach kernels out of speed reasons)

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