Obtain results from processes using python multiprocessing -

i trying understand how use multiprocessing module in python. code below spawns 4 processes , outputs results become available. seems me there must better way how results obtained queue; method not rely on counting how many items queue contains returns items become available , gracefully exits once queue empty. docs queue.empty() method not reliable. there better alternative how consume results queue?

import multiprocessing mp import time   def multby4_wq(x, queue):     print "starting!"     time.sleep(5.0/x)     = x*4     queue.put(a)   if __name__ == '__main__':     queue1 = mp.queue()     in range(1, 5):         p = mp.process(target=multbyc_wq, args=(i, queue1))         p.start()     in range(1, 5): # referring counting again         print queue1.get() 

instead of using queue, how using pool?

for example,

import multiprocessing mp import time   def multby4_wq(x):     print "starting!"     time.sleep(5.0/x)     = x*4     return  if __name__ == '__main__':     pool = mp.pool(4)     result in pool.map(multby4_wq, range(1, 5)):         print result 

pass multiple arguments

assume have function accept multiple parameters (add in example). make wrapper function pass arguments add (add_wrapper).

import multiprocessing mp import time   def add(x, y):     time.sleep(1)     return x + y  def add_wrapper(args):     return add(*args)  if __name__ == '__main__':     pool = mp.pool(4)     result in pool.map(add_wrapper, [(1,2), (3,4), (5,6), (7,8)]):         print result