Elixir concurrency demo: 1 million process spawn and garbage-collect.

elixir_concurrency_demo.exs

#!/usr/bin/env elixir

# make sure to bump max erlang processes limit first:
# export ERL_FLAGS="+P 2000000"

defmodule Concurrency do
  def millions_of_us(n) do
    receive do
      {sender_pid, message} ->
        Process.sleep(:rand.uniform(2000))
        send(sender_pid, "Process #{n} received message #{message}")
    end
  end

  def demo() do
    1..1_000_000
    |> Enum.map(fn n -> spawn(Concurrency, :millions_of_us, [n]) end)
    |> Enum.each(fn pid -> send(pid, {self(), "Hello!"}) end)

    receive_messages()
  end

  defp receive_messages do
    receive do
      message ->
        IO.puts(message)
        receive_messages()
    after
      3000 -> # After 3 seconds of no messages, end the function.
        IO.puts("No messages for 3 seconds. Done receiving messages.")
    end
  end
end && IO.puts("Concurrency module loaded.")
Process.sleep(3000)
Concurrency.demo()