O.S. support for lightweight processes

[emery@MBUNIX.MITRE.ORG (Emery)]

Bob Hathaway (rjh@purdue.edu) writes:
>I haven't looked at the POSIX standard yet but I'm hoping support
>for lightweight processes and distributed programming is provided.

The existing POSIX standard (P1003.1) does not include either
lightweight processes or distributed programming.  Nor will it any
time soon.  This is because the goal of the effort is to standardize
existing practice.  There is no industry consensus on lightweight
processes, the same way there is for other things, such as fork,
signals, etc, in Unix.  (Note that the POSIX signal model is different
from both System V and 4.2 BSD, but not radically so.  The differences
are in implementation.)

The POSIX Real-Time group (P1003.4) has been looking at threads, and
MAY include a threads/lightweight process interface in its document.
Although not a direct issue for the Ada binding, those of us working
on the Ada binding would very much like to see a threads interface
that can be used to implement Ada tasks.  Besides making the Ada RTS
implementor's life easier, hopefully the threads interface would
provide for single-level scheduling of all threads (both POSIX/C
threads and Ada tasks) across the entire system. 

I agree that current state-of-the-practice operating systems often get
in the way of Ada, but don't look at a Standards activity to fix this
problem until the state-of-the-practice is there.  

			Dave Emery
			emery@mitre.org
			POSIX Ada Binding (P1003.5) Technical Co-Editor

p.s.  If you believe this is a "good thing", then consider joining the
POSIX effort, either the working group or the balloting group.