Sample schedulers for Picos

Libraries

• Picos_mux_fifo Basic single-threaded effects based Picos compatible scheduler for OCaml 5.
• Picos_mux_multififo Basic multi-threaded effects based Picos compatible scheduler for OCaml 5.
• Picos_mux_random Randomized multi-threaded effects based Picos compatible scheduler for OCaml 5.
• Picos_mux_thread Basic Thread based Picos compatible scheduler for OCaml 4.

^{You may find these useful for both understanding the core Picos interface and for testing your own libraries implemented in Picos.}

Examples

Below is a program that forks a number of fibers and records a list of the domain ids on which the fibers run:

open Picos_std_structured
module Mpscq = Picos_aux_mpscq

let main ~work () =
  let dids = Mpscq.create () in

  Flock.join_after begin fun () ->
    for _ = 1 to 4 do
      Flock.fork @@ fun () ->
      let did = (Domain.self () :> int) in
      Unix.sleepf work; (* <- simulate work *)
      Mpscq.push dids did
    done
  end;

  Mpscq.pop_all dids
  |> List.of_seq
  |> List.sort Int.compare

We can now try running the program with the sample schedulers:

# Picos_mux_fifo.run (main ~work:0.0)
- : int list = [0; 0; 0; 0]
# Picos_mux_multififo.run_on ~n_domains:4 (main ~work:0.2)
- : int list = [0; 1; 2; 3]
# Picos_mux_random.run_on ~n_domains:4 (main ~work:0.2)
- : int list = [0; 4; 5; 6]
# Picos_mux_thread.run (main ~work:0.0)
- : int list = [0; 0; 0; 0]

A subtle detail above is that the Unix.sleepf call blocks the underlying thread for a moment, which makes it likely that multiple domains will be used by the multi-threaded schedulers. The results with the multi-threaded schedulers are still strictly speaking non-deterministic.