A simple Ruby class for managing work queues to be run in series or in parallel.

work_queue.rb

class WorkQueue

  attr_reader :result

  def initialize
    @q = []
  end

  def push &block
    @q << block
    @result= nil
  end

  def run_series
    @result = @q.map { |proc| proc.call }
  end

  def run_parallel(thread_limit=6, sleep_time=2)
    threads = []
    @q.each do |proc|
      until threads.map { |t| t.status }.count("run") < thread_limit do
        sleep sleep_time
      end
      threads << Thread.new(&proc)
    end
    @result = threads.map { |t| t.value }
  end

  def length
    @q.length
  end
end

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# Sample Usage                                                                #
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wq = WorkQueue.new

5.times do
  wq.push {
    # task code
    Math::PI
  }
end

p wq.run_series

p wq.run_parallel

p wq.result