I'v resolved the same problem using TCP/IP communication between
Ocaml thread and C thread.

Markus Mottl 쓴 글:

>Hi,
>
>I'm currently interfacing a 3rd-party library that spawns threads
>to execute callbacks.  I would like those callbacks to be handled by
>OCaml-code, but have run into some issues here.
>
>As it seems, it is not possible to run OCaml-code linked with thread
>support while letting C-threads perform callbacks.  This has already
>been a topic on the list a while ago.
>
>I have two solutions in mind: the first one would involve pre-spawning
>an OCaml-thread and pass data from C to OCaml through an OCaml-reference
>exposed to C, protected by mutexes and condition variables.  This seems
>pretty ugly, because it's error-prone and also involves a considerable
>amount of context-switching, which is bad for my application (very high
>volume realtime data).
>
>The second solution would require setting up an OCaml thread descriptor
>for the currently executing C-thread.  However, AFAIK this solution
>cannot be implemented without fiddling with the implementation of the
>OCaml-runtime, because some global variables for thread-handling are not
>exposed to user code (i.e. "static").  It would be great if the thread
>implementation offered functions allowing users to have their C-threads
>"migrate" to OCaml.
>
>Does anybody know of another elegant and efficient solution for this
>problem that does not require hacking the OCaml-runtime?
>
>Best regards,
>Markus
>
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>  
>