Parallel processing

parallel.ex

defmodule Worker do
  def work(num) do
    "Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo consequat."
    |> String.split
    |> Enum.map(&String.upcase/1)
    |> Enum.join
  end
end

iterations = 100000

{us, :ok} = :timer.tc fn ->
  0..iterations |>
    Stream.map(&Task.async(Worker, :work, [&1])) |>
    Enum.each(&Task.await(&1))
end

IO.puts "Time executing #{iterations} jobs in parallel: #{us/1000}ms"

{us, :ok} = :timer.tc fn ->
  0..iterations |>
    Enum.each(&Worker.work(&1))
end

IO.puts "Time executing #{iterations} jobs sequentially: #{us/1000}ms"

My results:

Task overhead with 10 Tasks: 0.465ms
Task overhead with 1000 Tasks: 9.069ms
Task overhead with 100000 Tasks: 624.897ms

In this version, sequential is, indeed faster:

Time executing 100000 jobs in parallel: 7767.314ms
Time executing 100000 jobs sequentially: 5176.606ms