title: Cannot get data from Queue
body: <p>I'm trying to use a joinable queue and i didn't get anything when join()
  is called on queue</p>
  
  <pre><code>from multiprocessing import JoinableQueue,Pool
  
  q = JoinableQueue()
  
  def pat(i):
      q.put("hello"+str(i))
      q.join()
      print(q.get())
  
  with Pool(5) as  p:
      (p.map_async(pat,range(5))).get()
  
  res = q.get()
  print(res+"main")
  q.task_done()
  </code></pre>
  
  <p>I get data from queue only after process exits</p>
  
  <p>Can anyone help me with this</p>