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Date: 6 Aug 91 04:05:50 GMT
From: june.cs.washington.edu!mfeldman@beaver.cs.washington.edu  (Mike Feldman)
Subject: Re: Ada and Unix--Blocked Tasks
Message-ID: <1991Aug6.040550.785@beaver.cs.washington.edu>
List-Id: <comp.lang.ada>

In article <780@esosun.UUCP> howard@hulder.css.gov (Howard Turner) writes:
>
> [stuff deleted]
>
>	"Tasking IS a part of Ada."  But it is not a part of the
>OS (usually).  The OS (except for maybe Rational's) has no notion 
>of Ada tasking, so why would you expect it not to block the entire process?
>In particular, Ada tasking is not a part of either VMS or Unix.  Neither
>OS will recognize the difference between an executable generated from C or 
>Ada or any other language.  Why would you expect the OS to handle executables
>derived from Ada source any differently than from C?
>
> [more stuff deleted]
>
What Paul might be getting at is the notion that an Ada compiler could
(should) map each Ada task onto an OS-level process. I see no reason in
principle why this could not be done; indeed, I think there may be vendors
who are doing it in Unix (can anyone confirm this?). I believe I heard
that one of the MVS (IBM mainframe) Ada systems can map Ada tasks to MVS
tasks (can anyone confirm?). In practice, I imagine that vendors are
keeping an ada program - tasks and all - in one OS-level process for
efficiency, reasoning that mapping tasks onto processes is overkill.

This is an area where I'd love to see some material that would let us in
on some of the "inside" discussions that must have taken place over the
years. Norm Cohen? Tucker Taft? Bob Eachus? How did the designers 
imagine the (possible) relationship(s) between tasks and processes?

Mike