operations.ml

open Core_kernel

let setup_logging () =
  let open Lwt_log in
  default := broadcast [channel ~close_mode:`Keep ~channel:Lwt_io.stderr ()];
  add_rule "*" Info

let threaded_function = fun pause ->
  Lwt_unix.sleep pause
  >> Lwt_log.info_f "Slept for %f" pause

let make_threads () =
  let () = Core_random.self_init () in
  let num_threads = Core_random.int 10 in
  let pauses_generator = Stream.from (fun n -> Some (Core_random.float 5.)) in
  let pauses = Stream.npeek num_threads pauses_generator in
  Core_list.map ~f:threaded_function pauses

let run_threads () =
  let threads = make_threads () in
  Lwt_main.run @@ (
    Lwt.join threads
    >> Lwt_log.info_f "%d threads run" @@ Core_list.length threads
  )

let bootup () =
  setup_logging ();
  run_threads ()

stdout.txt

git:(master) ✗ ./main.native
main.native: main: Slept for 0.419942
main.native: main: Slept for 1.676569
main.native: main: Slept for 2.655440
main.native: main: Slept for 3.553326
main.native: main: Slept for 4.232556
main.native: main: Slept for 4.356018
main.native: main: Slept for 4.673952
main.native: main: 7 threads run