> > Each thread is killed after work is done
> How do you "kill" the threads? I hope this is just a figure of
> speech for "I do an orderly shutdown of each thread after work is done."

Well, that was consequence of my bad English :-) Threads finish their
work and exit. I also made a simple wrapper to Thread.create to be sure
that all work inside threads is done:

module MyThread =
  let create f p =
    let dowork _ =
      (* log thread creation *)
      f p;
      (* log thread shutdown *)
    in
    Thread.create dowork ()
end