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Re: [Caml-list] STM support in OCaml
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Date: 2006-03-08 (10:11)
From: yoann padioleau <padator@w...>
Subject: Re: [Caml-list] STM support in OCaml

> > You make several claims:
> > 
> > STM is not lock free.
> > STM is not useful on a small number of processors
> > 
> > As for claim 1.  "Lock-free" doesn't mean what you think it does. 
> I know what STM does, thank you: I intend to implement it
> myself in my own programming language. Maybe you should
> read more carefully.
> I said "protected by a mutex under the hood." which means
> sure, the programmer is not writing locks, but they're used
> in the implementation and the associated costs are still paid.

I have read (very fastly) the atomcaml paper and I don't think they use "mutex under the hood".
It seems that they just log stuff and rollback. I guess that when you want to implement 
STM on multiprocessor you may need to mutex stuff (the internal data structures maintained by the STM runtime),
but as ocaml runtime does not use multiprocessor, they dont need it.