Sample schedulers for Picos

This package contains schedulers provided as samples 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.