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Date: Fri, 1 Jul 2011 16:06:40 +0400
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From: Dmitry Bely <dmitry.bely@gmail.com>
To: Damien Doligez <damien.doligez@inria.fr>
Cc: Caml List <caml-list@inria.fr>
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Subject: Re: [Caml-list] GC interface question

On Fri, Jul 1, 2011 at 3:49 PM, Damien Doligez <damien.doligez@inria.fr> wrote:
>
> On 2011-07-01, at 11:09, Dmitry Bely wrote:
>
>> Does this fragment violate GC interface rules:
>>
>>  Begin_roots_block(_varg, 2)
>>    _varg[0] = ((struct camlidl_intf *) this)->caml_object;
>>    _varg[1] = camlidl_alloc_small(1, Abstract_tag);
>>    Field(_varg[1], 0) = (value) log;
>>  End_roots();
>>  _vres = caml_callbackN_exn(caml_get_public_method(_varg[0],
>> Val_int(1007700946)), 2, _varg);
>>
>> It's unsafe to pass _varg to caml_callbackN_exn when it is not
>> referenced from local_roots, right?
>
>
> You're right, this code looks buggy.

I tend to think now that this part is OK; _varg is not used after
caml_callbackN_exn so local_roots are not needed. But what happens
inside caml_callbackN_exn()? How it assures that _varg is not
garbage-collected before the closure is applied?

This is camlidl-generated code (slightly modified to be thread-safe)
and I have an access violation (segmentation fault) error in
multi-threaded environment under heavy load. Just trying to figure out
what can be wrong here...

- Dmitry Bely