Newsgroups: comp.lang.c
Path: utzoo!henry
From: henry@utzoo.uucp (Henry Spencer)
Subject: Re: threads for C/C++ under Unix?
Message-ID: <1989Oct13.170846.29846@utzoo.uucp>
Organization: U of Toronto Zoology
References: <MONTNARO.89Oct12124156@sprite.crd.ge.com> <8720@goofy.megatest.UUCP>
Date: Fri, 13 Oct 89 17:08:46 GMT

In article <8720@goofy.megatest.UUCP> djones@megatest.UUCP (Dave Jones) writes:
>> You can't have preemptive lightweight processes without kernel support.
>
>Hmmm. What kind of kernel support do you need? All that's necessary, I think,
>is that it have a "select" routine which can wake up when potentially
>blocking system calls would not block. Like Unix does.

You need three pieces of kernel support:  a way to tell when a system call
would block, a way to initiate such an operation without waiting for
completion, and a way to be informed of completion.  "Unix" does *not*
have such things; some *variants* of Unix do... and some don't.
-- 
A bit of tolerance is worth a  |     Henry Spencer at U of Toronto Zoology
megabyte of flaming.           | uunet!attcan!utzoo!henry henry@zoo.toronto.edu