python 使用Pool，并需要关注结果

import multiprocessing
import time

def func(msg):
for i in xrange(3):
print msg
time.sleep(1)
return "done " + msg

if __name__ == "__main__":
pool = multiprocessing.Pool(processes=4)
result = []
for i in xrange(10):
msg = "hello %d" %(i)
result.append(pool.apply_async(func, (msg, )))
pool.close()
pool.join()
for res in result:
print res.get()
print "Sub-process(es) done."