ygrek a écrit :
> 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().

OK. Thanks....



-- 
      Guillaume Yziquel
http://yziquel.homelinux.org/