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From: "Dmitry A. Kazakov" <mailbox@dmitry-kazakov.de>
Subject: Re: Isn't this in favour of Ada??
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Date: Sat, 6 Aug 2005 13:02:52 +0200
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On Fri, 05 Aug 2005 18:58:50 +0200, Florian Weimer wrote:

> The original claim in this thread was that Ada is particularly
> suitable to the concurrency challenges ahead of us (I don't believe
> that there are any fundamentally new challenges, but let's assume that
> there are).  However, in order to create scalable applications, you
> have to use some features of today's operating systems, for example
> I/O multiplexing.  

Which is a case of more general waiting for multiple events. The problem is
that multiple-wait is a too low level mechanism. It is not very clear how
to map it on entry calls and accept.
 
> I am not aware of any Ada implementation which integrates I/O
> multiplexing with tasks. Therefore, it seems to me that Ada's tasking
> is a completely useless burden when developing concurrent applications
> on mainstream operating systems.  Usually, you have to figure out how
> to work around it realiably, so that the run-time library continues to
> work.

I disagree. Multitasking is more than just multiplexed I/O. If you look at
Windows (sort of mainstream) you find dozens of calls starting a thread.
Among them only 1 or 2 are actually usable. The synchronization mechanisms
Windows offers are all too low level. So for our C++ project of a
middleware (heavily multitasking), we end up with developing a library that
mimics Ada's rendezvous.

-- 
Regards,
Dmitry A. Kazakov
http://www.dmitry-kazakov.de