Trying running these programs on MRI and JRuby!

benchmark.rb

require 'benchmark'

def factorial_repeat(k, x)
  k.times { x.downto(1).inject(:*) }
end

def run(i, k, x)
  i.downto(1).map do
    Thread.new { factorial_repeat(k, x) }
  end.each { |t| t.join }
end

puts Benchmark.measure { run(1, 400_000, 99) }
puts Benchmark.measure { run(4, 100_000, 99) }

threads.rb

require 'benchmark'

def run(x)

  data = []
  (1..x).map do |m|
    Thread.new do
      x.times do |n|
        data << m * n
      end
    end
  end.each {|t| t.join}


  puts "size=#{data.size}"
  puts "nils=#{data.size-data.compact.size}"
end

puts Benchmark.measure { run(32) }