threads.rb

require 'benchmark'
require 'digest'
require 'etc'

THREAD_NUMBER = Etc.nprocessors

def count_md5(id)
  tmp = id.to_s
  1_000_000.times { tmp = Digest::MD5.hexdigest(tmp) }
  tmp
end

Benchmark.bm do |x|
  x.report do
    threads = []
    THREAD_NUMBER.times { threads << Thread.new { count_md5(Thread.current.object_id) } }
    threads.each(&:join)
  end
end