toolslive/gist:5908501

## gistfile1.ml
open Lwt

let n = 1_000_000_000

let time f =
  let t0 = Unix.gettimeofday () in
  let a = f () in
  let t1 = Unix.gettimeofday () in
  a,(t1-.t0)

let waste_cycles () =
  for vjvj = 0 to n do
    ignore (1 + 1)
  done

let loop until =
  let bs = 4096 in
  let buffer = String.create bs in
  let rec inner ic =
    if (Unix.gettimeofday ()) < until
    then
      begin
        Lwt_log.debug "hey" >>= fun () ->
        Lwt_io.read_into ic buffer 0 bs >>= fun bytes_read ->
        Lwt_io.printf "." >>= fun () ->
        Lwt_preemptive.detach (fun () -> time waste_cycles) ()
        >>= fun (_,d) ->
        Lwt_io.printlf "wasting_cycles took: %f" d >>= fun () ->
        inner ic
      end
    else Lwt.return "loop finished first"
  in
  Lwt_io.with_file ~mode:Lwt_io.input "/dev/zero" inner

let race loop_duration =
  let time = Unix.gettimeofday () in
  let make_loop () = loop (time +. loop_duration) in
  Lwt.pick [
    make_loop ();
    make_loop ();
    make_loop ();
    make_loop ();
    make_loop ();
    make_loop ();
    make_loop ();
    make_loop ();
    make_loop ();
    make_loop ();
    make_loop ();
    make_loop ();
    begin
      print_endline "going to sleep";
      let t0 = Unix.gettimeofday() in
      Lwt_unix.sleep 0.1 >>= fun () ->
      let t1 = Unix.gettimeofday() in
      let d = t1 -. t0 in
      let msg = Printf.sprintf "sleep finished first (%f)" d in
      Lwt.return msg
    end
  ]
  >>= fun s ->
  Lwt_io.printl s >>= fun () ->
  Lwt_io.printlf "pick took %f"  (Unix.gettimeofday () -. time)
  >>= fun () ->
  Lwt.return ();;

let main () =
  Lwt_main.run (race 1.);
  Lwt_main.run (race 2.);
  Lwt_main.run (race 3.);
  Lwt_main.run (race 4.)

in

main ()
	open Lwt

	let n = 1_000_000_000

	let time f =
	let t0 = Unix.gettimeofday () in
	let a = f () in
	let t1 = Unix.gettimeofday () in
	a,(t1-.t0)

	let waste_cycles () =
	for vjvj = 0 to n do
	ignore (1 + 1)
	done

	let loop until =
	let bs = 4096 in
	let buffer = String.create bs in
	let rec inner ic =
	if (Unix.gettimeofday ()) < until
	then
	begin
	Lwt_log.debug "hey" >>= fun () ->
	Lwt_io.read_into ic buffer 0 bs >>= fun bytes_read ->
	Lwt_io.printf "." >>= fun () ->
	Lwt_preemptive.detach (fun () -> time waste_cycles) ()
	>>= fun (_,d) ->
	Lwt_io.printlf "wasting_cycles took: %f" d >>= fun () ->
	inner ic
	end
	else Lwt.return "loop finished first"
	in
	Lwt_io.with_file ~mode:Lwt_io.input "/dev/zero" inner

	let race loop_duration =
	let time = Unix.gettimeofday () in
	let make_loop () = loop (time +. loop_duration) in
	Lwt.pick [
	make_loop ();
	make_loop ();
	make_loop ();
	make_loop ();
	make_loop ();
	make_loop ();
	make_loop ();
	make_loop ();
	make_loop ();
	make_loop ();
	make_loop ();
	make_loop ();
	begin
	print_endline "going to sleep";
	let t0 = Unix.gettimeofday() in
	Lwt_unix.sleep 0.1 >>= fun () ->
	let t1 = Unix.gettimeofday() in
	let d = t1 -. t0 in
	let msg = Printf.sprintf "sleep finished first (%f)" d in
	Lwt.return msg
	end
	]
	>>= fun s ->
	Lwt_io.printl s >>= fun () ->
	Lwt_io.printlf "pick took %f" (Unix.gettimeofday () -. time)
	>>= fun () ->
	Lwt.return ();;

	let main () =
	Lwt_main.run (race 1.);
	Lwt_main.run (race 2.);
	Lwt_main.run (race 3.);
	Lwt_main.run (race 4.)

	in

	main ()