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From: "Chris Thomasson" <cris...@comcast.net>
Newsgroups: comp.arch
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Subject: Re: How Many Processor Cores Are Enough?
Date: Mon, 20 Nov 2006 22:49:35 -0800
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"Brian Hurt" <bh...@spnz.org> wrote in message 
news:e0t8h.7975$lq.2268@newsread1.mlpsca01.us.to.verio.net...
> n...@cus.cam.ac.uk (Nick Maclaren) writes:
>
>
>>That experience debunked the claims of the
>>functional programming brigade that such methodology gave automatic
>>parallelisation.
>
> Automatic parallelization, no.  You're looking for a silver bullet that
> probably doesn't exist.  On the other hand, functional programming makes
> writting parallel code much easier to do.
>
> The biggest problem with parallelized code is the race condition- which
> arise from mutable data.  Every peice of mutable data is a race condition
> waiting to happen.  Mutable data needs to be kept to an absolute minimum,
> and then handled in such a way that it's correct in the presence of
> threads.
>
> I've come to the conclusion that functional programming is necessary-
> just not sufficient.

http://groups.google.com/group/comp.programming.threads/browse_frm/thread/b192c5ffe9b47926

Your conclusion is wrong. No need to be afraid of mutable data... Just stick 
it all in the writer side of a lock-free reader pattern.




> There are two languages I know of in which it may
> be possible to write non-trivial parallel programs correctly and
> maintainably- concurrent haskell with STM and erlang- and both are, at
> their core, purely functional languages.

STM is a no go. Way too much overhead... Here are some of the reasons why:


http://groups.google.com/group/comp.arch/msg/e1e391055c7acecb

http://groups.google.com/group/comp.programming.threads/browse_frm/thread/9c572b709248ae64

http://groups.google.com/group/comp.programming.threads/browse_frm/thread/f6399b3b837b0a40

http://groups.google.com/group/comp.arch/msg/1b9e405080e93149

http://groups.google.com/group/comp.arch/msg/bbbc035cf1a8502c

http://groups.google.com/group/comp.arch/msg/11b14c4bda2d5d82

http://groups.google.com/group/comp.arch/msg/9b00fda2752966f9

http://groups.google.com/group/comp.arch/msg/335aeb22fd6fe526

http://groups.google.com/group/comp.arch/msg/1ace9400b1b16cd4

http://groups.google.com/group/comp.arch/msg/995379a16beb3b69
(simply excellent Wheeler post)

...


Any thoughts?

;^)