[erlang-questions] Representation of a map in bytecode?

Robert Virding <>
Mon Sep 17 23:18:52 CEST 2007


There is another problem with automatic parallelisation and Erlang. As
Erlang DOES have side-effects, message passing basically, the order in which
things are evaluated is significant. It is therefore not safe to
automatically parallelise code. It is up to the programmer/designer to
decide how the application should be made parallel.

This is, of course, not always easy. Especially for most who come from a
sequential world where you usually work out how to make things sequential.
Yes I have been there. :-)

Robert

On 17/09/2007, Jouni Rynö <> wrote:
>
> On Mon, 2007-09-17 at 12:33 +0200, Kenneth Lundin wrote:
>
> > If the system design already allows thousands of parallell tasks it is
> > far from obvious that also the internal execution of each such task
> > should benefit from
> > automatic parallellisation. I actually believe that a system can be
> > over parallellized and that this will degrade the performance.
> >
> There used to be a beautiful processor architecture called Transputer
> and the language called Occam to program it. Making things going
> parallel was even more easier and natural than in Erlang.
>
> And there were many papers published, that going from extreme parallel
> systems to more serialised one was the way optimise the performance.
> Extreme parallel meaning systems, where you have decades more processes
> than real executing hardware. It all depends on the process switching
> time and communication overhead.
>
> regards
>         Jouni
> --
>
>   Jouni Rynö                            mailto://Jouni.Ryno@fmi.fi/
>                                         http://space.fmi.fi/~ryno/
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>
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