What is the state of OCaml's parallelization abilities?

Question

I\'m interested in using OCaml for a project, however I\'m not sure about where its parallelization capabilities are anymore. Is there a message passing ability in OCaml? Is O

Answer 1

This 2009 issue of the Caml weekly news ("CWN", a digest of interesting messages from the caml list) shows that:

• the official party line on threads and Ocaml hasn't changed. A notable quote:

  (...) in general, the whole standard library is not thread-safe. Probably that should be stated in the documentation for the threads library, but there isn't much point in documenting it per standard library module. -- X. Leroy

  (for how Ocaml threads can still be useful, see a remark by the culprit himself in another question on SO)

• the most frequently adopted paradigm for parallelism is message-passing, and of note is X. Leroy's OcamlMPI, providing bindings for programming in SPMD style against the MPI standard. The same CWN issue I pointed to above provides references to examples, and numerous other related projects.

• another message-passing solution is JoCaml, pioneering new style of concurrent communications known as join calculus. Note that it is binary-compatible with OCaml compilers.

• that did not prevent the confection of a runtime whose GC is ok with parallelism, though: see a discussion of OCAML4MC in this other issue of the CWN.

There is also:

• Netmulticore - multi-processing sharing ocaml values via mapped shared memory.

• CamlP3l - compiler for Caml parallel programs.

• OCaml-Java - an OCaml compiler that emits Java bytecode

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I haven't followed more recent discussions about Ocaml & parallel programming, though. I'm leaving this CW so that others can update what I mention. It would be great if this question could reach the same level of completeness as the analogous one for Haskell.