output.txt

λ elixir --erl '+P 2000000' -r spawn.ex -e 'Spawner.run(1000000)'
Memory after spawn [total: 2810825464, processes: 2772817683, processes_used: 2772817636, system: 38007781, atom: 331249, atom_used: 300914, binary: 1469240, code: 7652696, ets: 412072]
Time taken to spawn: 4.690528 s
Time to collect results: 5.752107 s
Memory in the end [total: 73518240, processes: 59105061, processes_used: 53168996, system: 14413179, atom: 331249, atom_used: 302425, binary: 1507208, code: 7802697, ets: 424408]
End result = 1000000

procs.ex

defmodule Spawner do
  def run(count) do
    run(count, count, :erlang.now)
  end

  def run(0, nroutines, tstamp) do
    IO.puts "Memory after spawn #{inspect :erlang.memory}"

    time = :erlang.now
    IO.puts "Time taken to spawn: #{ :timer.now_diff(time, tstamp)/1000000 } s"
    collect_results(nroutines, 0, time)
  end

  def run(count, nroutines, t) do
    pid = self()
    spawn(fn -> pid <- {self, 1}; receive do _ -> :ok end end)
    run(count-1, nroutines, t)
  end

  def collect_results(0, total, t) do
    time = :erlang.now
    IO.puts "Time to collect results: #{ :timer.now_diff(time, t)/1000000 } s"
    :erlang.garbage_collect
    IO.puts "Memory in the end #{inspect :erlang.memory}"
    IO.puts "End result = #{total}"
  end

  def collect_results(nroutines, total, t) do
    receive do
      {pid, x} ->
        pid <- :ok
        collect_results(nroutines-1, total+x, t)
    end
  end
end