Re: Ada tasking

[mph@lion.inmos.co.uk (Mike Harrison)]

In article <20075@grebyn.com> ted@grebyn.com (Ted Holden) writes:
>
> 
> 
>I must have been really tired the other night to have written the little
>formula for saving Ada and not mentioned tasking;  sorry.
> 
>From: Jeffrey M. Schweiger, Naval Postgraduate School, Monterey CA
> ... 
> 
>Probably the DOD got to him somehow or other;  maybe put a horses head
>in bed with him like in Godfather I ...  who knows;  made him promise to
>say SOMETHING nice about Ada and the statement about semetrically
>parallel machines (like the Sequent) was probably all he could think of.
>Ada DOES run reasonably well on the Sequent, but I should mention the
>following:

I have tried quite hard recently to avoid responding directly to this 
gentleman's postings but I regret that I cannot ingore this one.

Firstly, I cannot imagine how Mr. Holden hopes to make a case against Ada by
libelling a highly respected member of the international scientific community
(particularly one who he was recently quoting in support of his tendentious
arguments).

Secondly, and on a more technical point, he writes:

>Tasking is naturally an operating system feature;  the idea of tasking
>as a part of a language is one of the dumber ideas since communism.
>There's no right way to do it, as a careful reading of the 750 little
>"problems" should make obvious to anybody.  In all truth, I can't really
>believe that any of the serious people in this group who have read
>through any of that would argue this point with me.  Probably what you
>want to do is to define a standard set of features to be provided by
>operating systems/real-time kernals for uses which involve tasking, a
>standard set of function calls, and have libraries to provide these
>functions to applications which need them.


Thus dismissing in one breath, all the work being done on parallel and
comcurrent processing. No qualification, no justification -- no sign of
understanding!

'Tasking' is merely a name for methods of expressing the notions of concurrent
or co-lateral execution. Such notions, if given a suitable medium of expression,
can be as powerful a form of abstraction for controlling the complexity of some
kinds of application as procedures and structured data types are for others.

The ability to choose an appropriate level of granularity for such co-lateral
threads of computation is just as important as the ability to use procedures
and functions whose bodies may be quite trivial, but which improve the clarity
of expression. (Perhaps Mr. Holden never uses macros in any of his C programs).

'Fine grain' parallelism clearly cannot be achieved by relying on the services
offered by operating systems or 'run-time kernels', (at least for the general
run of machines to which Mr. Holden would have us restrict ourselves). [ the
Sequent is too expensive, etc.].

It follows that to the full range of expression which programmers and engineers
now require can only be met by integrating the mechanisms of parallelism into
the language.
This Ada has done.

I am puzzled by Mr. Holden's motives in continuing to post his poisonous libels
in this group. I am sure that no-one objects to intelligent criticism of Ada,
even if it is primarily destructive in nature, so long as it is expressed in a
civil manner, but Mr. Holden acts in a way more befitting a fractious 4 year
old child.

More in sorrow than in anger,

Mike,



Michael P. Harrison - Software Group - Inmos Ltd. UK.
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