Re: [Caml-list] Potential OCaml-ZMQ memory management problems

[Kenneth Adam Miller <kennethadammiller@gmail.com>]

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Actually, I literally just found the location of the error... I'm trying to
send some data from ocaml that is causing ZMQ to segfault...

On Thu, Dec 4, 2014 at 11:39 AM, Kenneth Adam Miller <
kennethadammiller@gmail.com> wrote:

> ok, I tried it with Gc.major() and Gc.minor(); and that didn't eliminate
> the segfault.
>
> There's an issue with debugging too; when I compile my unit tests for
> debugging or byte code, it reports parameters not being found (as in the
> string returned from ZMQ is empty), even though a simple recompile with
> native code makes that specific mysterious error go away. In any case,
> because it does not receive the parameters while compiled for debug or byte
> code, it cannot proceed to the point where the segfault occurs. Also, just
> removing some of the preceeding tests in order that they not be in the way
> when compiled for byte or debug code causes the segfault to not occur...
>
> How do I debug this in binary mode?
>
> On Thu, Dec 4, 2014 at 5:04 AM, Kenneth Adam Miller <
> kennethadammiller@gmail.com> wrote:
>
>> Ok I'll give that a shot when I get a chance to edit it. Thanks,
>> gc.major... I'm new to ocaml and I'm still reading through RWO, on chapter
>> 9 learning about how modules compose nicely :)
>>
>> On Thu, Dec 4, 2014 at 4:59 AM, Anders Fugmann <anders@fugmann.net>
>> wrote:
>>
>>> The garbage collector settings seems quite sane to me. You could try to
>>> force a major collection every call to iltrans.
>>>
>>> Gc.major ()
>>>
>>> It could be that the segfault is really an out of memory situation.
>>> Maybe you have a leak in your code somewhere (Not releasing references to
>>> large objects).
>>>
>>> /Anders
>>>
>>>
>>> On 12/04/2014 09:02 AM, Kenneth Adam Miller wrote:
>>>
>>>> I'm using zmq and ocaml-zmq as installed by opam; I'm not at my work
>>>> computer or I would provide those details.
>>>>
>>>> Yes, I will try to work on creating a reproducible script
>>>>
>>>> Could it possibly be a call to Tunegc.set_gc () from
>>>> https://github.com/argp/bap/blob/master/ocaml/tunegc.ml ?
>>>>
>>>> I notice that this error didn't appear in single calls to my utility;
>>>> basically, I'm using iltrans from bap and I'm using it in a long living
>>>> process, unlike the current implementation which expects a few
>>>> transformations and then process death. I did notice that when I run it,
>>>> if I'm watching system monitor that it begins consuming vast amounts of
>>>> memory (quickly grows from a few megabytes to 800+) before it hits
>>>> segfault. Would there be any way to restore the aggressiveness of the GC
>>>> between calls to iltrans?
>>>>
>>>> On Thu, Dec 4, 2014 at 2:55 AM, Anders Fugmann <anders@fugmann.net
>>>> <mailto:anders@fugmann.net>> wrote:
>>>>
>>>>     Hi Kenneth,
>>>>
>>>>     The Ocaml-zmq code copies data from received messages into memory
>>>> under
>>>>     the control of the ocaml garbage collector, and immediatly frees the
>>>>     ZMQ buffers.
>>>>
>>>>     You do not need to explicitly free the data received from call to
>>>> recv.
>>>>
>>>>     Can you produce a small sample code that exposes the problem? We are
>>>>     using the ocaml-zmq binding extensively, and have not seen any
>>>> problems.
>>>>
>>>>     If I were to take a wild guess, it either a mismatch between library
>>>>     versions or the garbage-collector collecting the socket or zmq
>>>> context.
>>>>
>>>>     What version of the ocaml-zmq bindings and libzmq (c impl) are you
>>>>     using?
>>>>
>>>>     /Anders
>>>>
>>>>
>>>>
>>>>     On 12/04/2014 07:09 AM, Kenneth Adam Miller wrote:
>>>>
>>>>         I'm using ocaml-zmq (https://github.com/issuu/__ocaml-zmq
>>>>         <https://github.com/issuu/ocaml-zmq>) and I think I'm
>>>>         encountering a memory management issue. I could be wrong
>>>>         however, but
>>>>         basically the issue (I think) is I have a rather large set of
>>>>         messages
>>>>         to send via zmq, and I'm getting a segfault.
>>>>
>>>>         Does anybody know if I need to free the strings received from
>>>>         zmq recv
>>>>         functions in ocaml? If so how do I do that from ocaml?
>>>>
>>>>         There's no code because this is just a general novice ocaml
>>>>         questions.
>>>>
>>>>
>>>>
>>>>
>>>
>>
>

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