Path: utzoo!attcan!uunet!husc6!cmcl2!nrl-cmf!ames!oliveb!pyramid!prls!philabs!spies!ssdis!gsarff
From: gsarff@ssdis.UUCP (gary sarff)
Newsgroups: comp.sys.amiga
Subject: Re: Amiga UNIX
Summary: 2 threads are cheap
Message-ID: <142@ssdis.UUCP>
Date: 24 Jun 88 21:04:47 GMT
References: <23602@hi.unm.edu> <4071@cbmvax.UUCP>
Organization: SSDIS-Special Security Department,Internal Security
Lines: 32

In article <4071@cbmvax.UUCP>, daveh@cbmvax.UUCP (Dave Haynie) writes:
> in article <23602@hi.unm.edu>, erikj@hi.unm.edu (Erik Johannes) says:
> 
> > One of the principal foundations of UNIX is cheap processes,
> 
> Compared to the above, perhaps.  But UNIX processes are certainly more
> expensive than AmigaOS processes.  Which is why they created "threads"
> in Mach.

Threads are like shared libraries in the sense that they give you an 
advantage if you have more than 1 process using them.  A shared library
with only one process using it gives you nothing more than if the library
routines were actually in the programs load image.  With 2 or more programs
you reap an advantage.  Same with threads, if you have only 1 thread in
a process, it isn't any "cheaper" than a unix process.  It still has a
process or task control block, a stack, a heap, a place to store its
registers when it is context switched etc, just like a heavy process.  Only
if the process is really executing multiple threads of itself do you get
any advantage at all.  If I have on my amiga running, 1 word processor,
1 spreadsheet, 1 photon paint, 1 comm program, they are all different
processes all single threaded, no advantage is gained.  Threads would be
much better if one had fork() in an OS like unix, then the OS could just
create another thread of the calling process instead of copying the 
core image again.  Threads are nicer yes, but do many amiga programs use
them, i.e. are there any multi-threaded "application" programs?


-- 
Gary Sarff           {uunet|ihnp4|philabs}!spies!ssdis!gsarff
To program is human, to debug is something best left to the gods.
"Spitbol?? You program in a language called Spitbol?"
  The reason computer chips are so small is that computers don't eat much.