python 中的pipe

 from multiprocessing import Process,Queue,Pipe
 import os
 def f(q):
 #    q.send([42,None,'hello'])
     print('This is child_conn ....' % q.recv())
 #    q.close()
     print 'Os getpid is %s...' % os.getpid()

 if __name__=='__main__':
     parent_conn,child_conn=Pipe()
     parent_conn.send(['good',None,100])
     p=Process(target=f,args=(child_conn,))
     p.start()
     print(parent_conn.recv())
     parent_conn.close()
     p.join()

?f(q)内的作为child_conn的q为什么接收不到parent_conn的推送