open Lwt.Infix

let program =
  let parent_pid = Unix.getpid () in

  let some_func () =
    Printf.sprintf "Process: %d" (Unix.getpid ())
    |> Lwt_io.printl >>= fun () -> Lwt_io.flush Lwt_io.stdout
  in
  let marshaled = Marshal.to_bytes some_func [Marshal.Closures] in

  Printf.sprintf "Parent pid:%d" parent_pid
  |> Lwt_io.printl >>= fun () ->

  Lwt_io.flush Lwt_io.stdout >>= fun () ->

  let fd = Lwt_unix.socket Lwt_unix.PF_UNIX Lwt_unix.SOCK_STREAM 0 in

  for i = 0 to 3 do
    let pid = Lwt_unix.fork () in
    if pid = 0 then
      Lwt.async (fun () ->
          Lwt_unix.accept fd >>= fun (sock, addr) ->
          let b = Bytes.create (Bytes.length marshaled) in
          Lwt_unix.read sock b 0 (Bytes.length marshaled) >>= fun _ ->
          let func : unit -> unit Lwt.t = Marshal.from_bytes b 0 in
          func ()
        )
  done;

  Lwt_unix.write fd marshaled 0 (Bytes.length marshaled) >>= fun _ ->

  Lwt_unix.sleep 10.0


let () = Lwt_main.run program



Parent pid:6159
Fatal error: exception Unix.Unix_error(Unix.ENOTCONN, "write", "")
Raised at file "src/core/lwt.ml", line 801, characters 16-23
Called from file "src/unix/lwt_main.ml", line 34, characters 8-18
Called from file "example/e.ml", line 148, characters 9-29
Fatal error: exception Unix.Unix_error(Unix.EINVAL, "accept", "")
Raised by primitive operation at file "src/unix/lwt_unix.ml", line 1370, characters 50-67
Called from file "src/unix/lwt_unix.ml", line 551, characters 17-28
Fatal error: exception Unix.Unix_error(Unix.EINVAL, "accept", "")
Raised by primitive operation at file "src/unix/lwt_unix.ml", line 1370, characters 50-67
Called from file "src/unix/lwt_unix.ml", line 551, characters 17-28
Fatal error: exception Unix.Unix_error(Unix.EINVAL, "accept", "")
Raised by primitive operation at file "src/unix/lwt_unix.ml", line 1370, characters 50-67
Called from file "src/unix/lwt_unix.ml", line 551, characters 17-28
Fatal error: exception Unix.Unix_error(Unix.EINVAL, "accept", "")
Raised by primitive operation at file "src/unix/lwt_unix.ml", line 1370, characters 50-67
Called from file "src/unix/lwt_unix.ml", line 551, characters 17-28