Path: utzoo!attcan!uunet!ncrlnk!ncrpcd!wright!jsloan@wright.UUCP
From: jsloan@wright.UUCP (John Sloan)
Newsgroups: comp.sys.misc
Subject: Re: NeXT & "threads"
Message-ID: <365@thor.wright.EDU>
Date: 31 Oct 88 15:11:11 GMT
References: <19648@apple.Apple.COM>
Sender: news@wright.EDU
Reply-To: jsloan@wright.UUCP
Lines: 40

desnoyer@Apple.COM (Peter Desnoyers):
> In article <363@thor.wright.EDU> jsloan@wright.UUCP writes:
>>Threads are neat. Not necessarily new, although MACH and OS/2 are the
>>first "commercial" operating systems that I'm aware to feature them,
>>but still neat.
> 
> Most real-time kernels (commercial or not) use threads and call them
> tasks. Ada, Simula, Modula 2, Smalltalk and probably other languages
> provide "processes" which seem to fit the definition of a thread, but
> as a language feature rather than an OS feature.
> 

Yep, although in our own real-time kernel (there's no name for it...
it's something we originally developed ten years ago and have used it
widely), which we've ported across PDP/LSI-11s and 68000s, in
assembler, C and Forth, we just call them "processes", since they're
usually implemented on machines which do not provide such support (and
hence there is no name conflict... I suppose on IBM mainframes you'd
have to use some other term than "task" :-).

Anyway, our own real-time "processes" are indeed threads, or processes
that run in the same address space. On the implementations we have that
run on top of Unix (currently on VAX/Ultrix, Sun-3/SunOS, and NCR
Tower/System V engines), we use the term "lightweight processes" to
differentiate between normal Unix processes. "Thread" would do just as
well, I suppose.

We use Ada and Modula-2 as well (and Concurrent C and Concurrent
Prolog, etc.), but the lightweight processes in these are supported via
language specific library calls, not by a general, consistent system
interface.

Copyright 1988 by John Sloan ...!ucsd!ncr-sd!ncrlnk!ncrpcd!wright!jsloan
Wright State University Research Center   jsloan%wright.edu@relay.cs.net
3171 Research Blvd., Kettering, OH 45420       ...!osu-cis!wright!jsloan
Logical Disclaimer: belong(opinions,jsloan). belong(opinions,_):-!,fail.
Copyright 1988 by John Sloan ...!ucsd!ncr-sd!ncrlnk!ncrpcd!wright!jsloan
Wright State University Research Center   jsloan%wright.edu@relay.cs.net
3171 Research Blvd., Kettering, OH 45420       ...!osu-cis!wright!jsloan
Logical Disclaimer: belong(opinions,jsloan). belong(opinions,_):-!,fail.