What is the cleanest way to stop a python multiprocessing worker attached to a queue in an infinite loop? -

i'm implementing producer-consumer pattern in python using multiprocessing.pool , multiprocessing.queue. consumers pre-forked processes uses gevent spawn multiple tasks.

here trimmed down version of code:

import gevent queue import empty queueempty multiprocessing import process, queue, pool import signal import time  # task queue queue = queue()  def init_worker ():     # ignore signals in worker     signal.signal( signal.sigterm, signal.sig_ign )     signal.signal( signal.sigint, signal.sig_ign )     signal.signal( signal.sigquit, signal.sig_ign )  # 1 of worker task def worker_task1( ):     while true:         try:             m = queue.get( timeout = 2 )              # break out if producer says quit             if m == 'quit':                 print 'time quit'                 break          except queueempty:             pass  # worker def work( ):     gevent.joinall([         gevent.spawn( worker_task1 ),     ])  pool = pool( 2, init_worker ) in xrange( 2 ):     pool.apply_async( work )  try:     while true:         queue.put( 'some task' )         time.sleep( 2 )  except keyboardinterrupt e:     print 'stopping'      # signal workers quit     in xrange( 2 ):         queue.put( 'quit' )      pool.join() 

now when try quit it, following state:

1. parent process waiting 1 of children join.
2. one of children in defunct state. finished parent waiting other child finish.
3. other child showing: futex(0x7f99d9188000, futex_wait, 0, null ....

so correct way end such process cleanly?

i figured out problem. according documentation multiprocessing.pool.join(), pool needs close()ed before can join()ed. adding pool.close() before pool.join() solved problem.