parallel_workers.rb

require 'thread'

params_for_job = Queue.new
workers = []
def perform_task(params_for_job)
  while x = params_for_job.pop
    print x + "\n"
  end
  return x
end

30.times do |i|
  params_for_job.push("a"*i)
end

4.times do
  workers << Thread.new do
    x = perform_task(params_for_job)
  end
end

workers.map { |thr| thr.join(1) }