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From: ygrek <ygrekheretix@gmail.com>
To: caml-list@yquem.inria.fr
Subject: Re: [Caml-list] problem creating .cma library
Date: Sun, 10 Jan 2010 15:31:05 +0200	[thread overview]
Message-ID: <20100110153106.bc7576e7.ygrekheretix@gmail.com> (raw)
In-Reply-To: <4B48DAA7.3070400@citycable.ch>

On Sat, 09 Jan 2010 20:36:07 +0100
Guillaume Yziquel <guillaume.yziquel@citycable.ch> wrote:

> So if I want to call R code that multithreads with OCaml, I should write 
> something like
> 
> >   enter_blocking_section();
> >   PROTECT(e = R_tryEval(Sexp_val(sexp_list), R_GlobalEnv, &error));
> >   UNPROTECT(1);
> >   leave_blocking_section();
> 
> Am I correct?

I bet no. It is not safe to access block ocaml value
inside blocking_section. In this particular case Sexp_val(v) is Field
(v,0) whis in turn is v[0] or *v. So you read the pointer, then in
another thread GC moves things around and old copy of the pointed
value is overwritten, then you read the value through 
the old pointer and get garbage.
Put Sexp_val call before caml_enter_blocking_section().

-- 
 ygrek
 http://ygrek.org.ua


  parent reply	other threads:[~2010-01-10 13:31 UTC|newest]

Thread overview: 21+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2009-12-30 17:48 rouanvd
2009-12-30 23:30 ` [Caml-list] " Guillaume Yziquel
2010-01-05 13:04   ` Damien Doligez
2010-01-08 23:38     ` Guillaume Yziquel
2010-01-08 23:54       ` Basile STARYNKEVITCH
2010-01-09  0:11         ` Guillaume Yziquel
2010-01-09  7:58           ` David Allsopp
2010-01-09 11:33             ` Guillaume Yziquel
2010-01-09 12:52               ` Richard Jones
2010-01-09 14:00                 ` Daniel Bünzli
2010-01-09 14:02                   ` Daniel Bünzli
2010-01-09 14:21                     ` Joel Reymont
2010-01-09 19:36                   ` Guillaume Yziquel
2010-01-10  2:11                     ` Daniel Bünzli
2010-01-11 17:14                       ` Guillaume Yziquel
2010-01-10 13:31                     ` ygrek [this message]
2010-01-11 18:01                       ` Guillaume Yziquel
2010-01-09 19:29                 ` Guillaume Yziquel
2010-01-11 12:18                   ` Gerd Stolpmann
2010-01-11 17:11                     ` Guillaume Yziquel
2010-01-20 14:42                   ` Damien Doligez

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