offers concurrent execution method to Enumerable object

concurrent_executor.rb

module ConcurrentExecutor

  def concurrent_each(concurrency, queue_size, &proc)
    require "thread"
    queue = SizedQueue.new(queue_size)
    queueing_thread = Thread.start{ 
      each{|item| queue.enq([item, true]) }
      concurrency.times{ queue.enq([nil, false]) } # send termination signal
    }   

    workers = []
    concurrency.times do  
      workers << Thread.start{ 
        while true do
          task, continue_flag = queue.deq()
          break if !continue_flag
          proc.call(task) 
        end 
      }   
    end 

    workers.each{|worker| worker.join }
    queueing_thread.join
    self
  end 

end

# Sample:
# class Array; include ConcurrentExecutor; end
# [1, 2, 3].concurrent_each(2, 10){|n| sleep(rand(10)); puts n }