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From: Matthias Kretschmer <McCratch@gmx.net>
Newsgroups: comp.lang.ada
Subject: Re: Ada Tasks vs Linux processes
Date: Tue, 03 Apr 2001 12:28:02 +0100
Organization: RHRZ - University of Bonn (Germany)
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Date: 2001-04-03T10:23:47+00:00
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Frank wrote:

> Hi!
>
> It seems to me (after some more searching in select -statement variations)
> that the I should use the construction select...or.._else_ to achieve what I
> intended.
>
> But this disussion brings another question to my mind; from some e-threads I
> read here I have got the impression that I _have_ to perform delay n; in the
> code so that all tasks get a slice of the execution (perhaps this goes for
> OS or CPU that does not handle HW multitasking or something?) Is this a
> true, or can I assume that Ada (and/or the OS it is running in) slices
> executions on every platform it is implemented?
> I can understand that a delay n; makes good sense if a task does not have to
> execute continously and a delay therefore can give execution slices to other
> tasks instead.
>

It is true, that on systems which do not support preemptive multitasking or on
which you ada-compiler doesn't support this, you need delay statements to switch
between threads. (e.g. the gnat on FreeBSD (from ports-collection 4.2-stable)
doesn't support the os-implementation of threads and simulates non-preemptive -
without delay statements on this system with this compiler your active thread
won't change)

>
> Frank