slowdowns.exs

Mix.install([:table_rex])

defmodule Benchmark do

  def run(iterations, fun) do
    durations = Enum.map(1..iterations, fn _ -> measure_time(fun) end)
    %{
      "average (us)" => Enum.sum(durations) / iterations,
      "median (us)" => Enum.sort(durations) |> Enum.at(round((iterations - 1) / 2)),
      "min (us)" => Enum.min(durations),
      "max (us)" => Enum.max(durations)
    }
  end

  def show(measurements) do
    {header, data} = Enum.unzip(measurements)
    TableRex.quick_render!([data], header)
    |> IO.puts()
  end

  defp measure_time(fun) do
    {duration, _} = :timer.tc(fun)
    duration
  end
end

System.version()

old = "some-short-string"
new = "a-bit-longer-but-short-still"

Benchmark.run(500_000, fn -> String.myers_difference(old, new) end) |> Benchmark.show()
Benchmark.run(500_000, fn -> Task.async(fn -> String.myers_difference(old, new) end) |> Task.await() end) |> Benchmark.show()

Output with an M1 Max MBP, macOS 13.0.1, Elixir 1.14.1, Erlang 25.1.1:

+--------------+----------+-------------+----------+
| average (us) | max (us) | median (us) | min (us) |
+--------------+----------+-------------+----------+
| 10.38885     | 3709     | 10          | 9        |
+--------------+----------+-------------+----------+

+--------------+----------+-------------+----------+
| average (us) | max (us) | median (us) | min (us) |
+--------------+----------+-------------+----------+
| 25.33128     | 2931     | 25          | 24       |
+--------------+----------+-------------+----------+