当子类multiprocess.Process，Pipe无法正常工作时的Python问题

Question

main_task.py

from process_template import ProcessTemplate

if __name__ == '__main__':

    data = {'input': [2,0,1,9], 'result':[]}

    child_1 = ProcessTemplate(data)
    child_1.start()

    while (1):
        msg = raw_input()

    if msg == "Q":
        child_1.get_parent_send_conn().send("Stop now!")

    if child_1.get_parent_recv_conn().poll():
        print "Parent gets", child_1.get_parent_recv_conn().recv()

process_template.py

from multiprocessing import Process, Pipe
import time

class ProcessTemplate(Process):

    def __init__(self, data, *args, **kwargs):       

    self.parent_recv_conn, self.child_send_conn = Pipe()
    self.parent_send_conn, self.child_recv_conn = Pipe()

    self.data = data

    Process.__init__(self)


    def get_parent_send_conn(self):
        return self.parent_send_conn


    def get_parent_recv_conn(self):
        return self.parent_recv_conn


    def get_child_send_conn(self):
        return self.child_send_conn


    def get_child_recv_conn(self):
        return self.child_recv_conn


    def run(self):

    print self.data

        time.sleep(2)
    print "step", 1
    self.child_send_conn.send("step 1 done")
    if self.child_recv_conn.poll():
        print "Child gets", self.child_recv_conn.recv()

    time.sleep(2)       
    print "step", 2
    self.child_send_conn.send("step 2 done")
    if self.child_recv_conn.poll():
        print "Child gets", self.child_recv_conn.recv()

    time.sleep(2)    
    print "step", 3
    self.child_send_conn.send("step 3 done")
    if self.child_recv_conn.poll():
        print "Child gets", self.child_recv_conn.recv()

    time.sleep(2)    
    print "step", 4
    self.child_send_conn.send("step 4 done")
    if self.child_recv_conn.poll():
        print "Child gets", self.child_recv_conn.recv()

使用上面的代码，主要任务无法从子进程接收消息。

帮助表示感谢！