Parallelism with Ruby

test.rb

require 'benchmark'
require 'parallel'

def expensive_calculation(letter)
  letter *= 1_000_000_000
  puts letter[rand(0..999_999_999)]
end

Benchmark.bm do |x|
  x.report("With Parallel: \n", in_thread: 3) do
    Parallel.map(%w(a b c)) do |letter|
      expensive_calculation(letter)
    end
  end

  x.report("Without Parallel: \n") do
    %w(a b c).map do |letter|
      expensive_calculation(letter)
    end
  end
end