Re: [Caml-list] Efficient OCaml multicore -- roadmap?

[Lucas Dixon <ldixon@inf.ed.ac.uk>]

On 24/03/2011 19:13, Fabrice Le Fessant wrote:
> On 03/24/2011 02:45 PM, Alexy Khrabrov wrote:
>>> Where does the OCaml team stand on the multicore issues?  A year
>>> or so ago, when there was a prototype parallel GC implementation,
>>> IIRC, Xavier said it has to be done right.  So what are the
>>> official plans and the status of integrating what volunteers had
>>> done?
>>>
>>> WIth Scala having a robust actors model and AKKA kernel, and
>>> Clojure built around efficient shared memory concurrency with
>>> agents and references and STM, and Haskell also really parallel,
>>> OCaml is lacking behind.  Furthermore, F# builds on strongly
>>> parallel .NET, overcoming granddaddy.  With multicores common
>>> even in laptops and iPads, we need an efficient  multicore OCaml!
>>> Due to the model different from Haskell or Scala and Clojure, now
>>> all on github, OCaml is both more stable and also is slower to
>>> advance -- what do folks think about this situation?  How do you
>>> do shared memory parallelism now?
>>>
>>> Cheers, Alexy
>>>

The PolyML implementation of SML has had a multi-core runtime, without 
slowing down single-threaded programs for a few years now. It also has a 
concurrent garbage collector. The main problem currently seems to be 
that a lot of garbage gets produced, and memory access speeds end up 
being the main bottle-neck. But we do see 4-5x speed-up on 8 core 
machines for large real-world applications (in SML, our real world means 
a big formal proof development, or graph rewriting at the moment... but 
there's more fun stuff possible: http://kidkarolis.github.com/PolyChrome/)

Anyway, I suspect you'll run into some of the same issues as PolyML 
encountered; there's a paper or two by David Matthews on this stuff; 
(here's the first one I found: 
http://portal.acm.org/citation.cfm?id=1708058&dl=ACM) and of course 
there is the source code too:
http://polyml.svn.sourceforge.net/viewvc/polyml/

Good luck with the OCaml version; it's been wanted for a long time! :)

best,
lucas



-- 
The University of Edinburgh is a charitable body, registered in
Scotland, with registration number SC005336.