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From: Francis Dupont <Francis.Dupont@fdupont.fr>
To: Wolfgang Draxinger <wdraxinger.maillist@draxit.de>
cc: Caml List <caml-list@inria.fr>
In-reply-to: Your message of Fri, 04 Oct 2013 01:46:49 +0200.
             <20131004014649.2b4e7750@narfi.yggdrasil.draxit.de> 
Date: Fri, 04 Oct 2013 17:44:27 +0200
Sender: Francis.Dupont@fdupont.fr
Subject: Re: [Caml-list] Current state of threading parallelism?

 In your previous mail you wrote:

>  I'm a bit out of the loop of the current state of OCaml support for
>  parallelism. My most recent knowledge on the topic, which dates back
>  about 3 years, would be, that due to the global garbage collector OCaml
>  did support only time sharing multithreaded concurrency limited to a
>  single processing core, i.e. no parallelism at all.

=> yes, this is the official way (no shared memory, no fine grain
locking, etc). Note this was the way followed by Python too for
the same reasons (to make the intepreter multi-threaded was considered
as too hard for the expected best result, i.e., ~4 time maximum speed up).
You can say OCaml can be compiled to native code but this is far to help
for the garbage collector...

>  Have there been significant changes in that regard lately? I did notice
>  that there are now new (inofficial) ocamlopt backends based on LLVM.
>  Are there any new, as exciting developments regarding the runtime system
>  as well?

=> I can't see where a LLVM backend really helps for multi-core/multi-
processor parallelism... IMHO the best / most reasonable thing you can
do to handle multi-core/multi-processor parallelism is a set of
communicating independent OCaml instances (one per process). The model
is well understood and scales.

Regards

Francis.Dupont@fdupont.fr

PS: my PhD thesis was about Caml and parallelism so the subject is
really not new...