Run concurrently with a progress bar.

gistfile1.rb

def run_concurrently(title, jobs, &block)
  mutex = Mutex.new
  work = Queue.new
  jobs.each {|j| work << j}
  pbar = ProgressBar.create(title: title, total: jobs.length, format: '%a |%w>%i| %e %t')
  threads = 4.times.map do
    Thread.new do
      loop do
        block.call(work.pop(:nonblocking))
        mutex.synchronize { pbar.increment }
      end
    end
  end
  sleep 5 while threads.any?(&:alive?) 
  pbar.finish
end