确保ZeroMQ中的工作进程总是正常终止

Question

我正在用Python的zeroMQ实现一个管道模式。

任务会分发给多个工作者，这些工作者会通过一个无限循环来监听新的任务，代码大概是这样的：

    while True:
        socks = dict(self.poller.poll())
        if self.receiver in socks and socks[self.receiver] == zmq.POLLIN:
            msg = self.receiver.recv_unicode(encoding='utf-8')
            self.process(msg)
        if self.hear in socks and socks[self.hear] == zmq.POLLIN:
            msg = self.hear.recv()
            print self.pid,":",  msg
            sys.exit(0)

当他们收到来自“汇聚节点”的消息，确认已经收到了所有预期的结果时，就会退出。

不过，有时候工作者可能会错过这样的消息，导致没有完成任务。那么，有什么好的方法可以确保工作者总是能完成任务呢？因为除了前面提到的消息，他们没有其他方式知道没有更多的任务需要处理。

这是我写的测试代码，用来检查工作者的状态：

#-*- coding:utf-8 -*-
"""
Test module containing tests for all modules of pypln 

"""
import unittest
from servers.ventilator import Ventilator
from subprocess import Popen, PIPE
import time
class testWorkerModules(unittest.TestCase):
    def setUp(self):
        self.nw = 4
        #spawn 4 workers
        self.ws = [Popen(['python', 'workers/dummy_worker.py'], stdout=None) for i in range(self.nw)]
        #spawn a sink
        self.sink = Popen(['python', 'sinks/dummy_sink.py'], stdout=None)
        #start a ventilator
        self.V = Ventilator()
        # wait for workers and sinks to connect
        time.sleep(1)

    def test_send_unicode(self):
        '''
        Pushing unicode strings through workers to sinks.
        '''

        self.V.push_load([u'são joão' for i in xrange(80)])
        time.sleep(1)
        #[p.wait() for p in self.ws]#wait for the workers to terminate
        wsr = [p.poll() for p in self.ws]
        while None in wsr:
            print wsr, [p.pid for p in self.ws if p.poll() == None] #these are the unfinished workers
            time.sleep(0.5)
            wsr = [p.poll() for p in self.ws]
        self.sink.wait()
        self.sink = self.sink.returncode
        self.assertEqual([0]*self.nw, wsr)
        self.assertEqual(0, self.sink)

if __name__ == '__main__':
    unittest.main()

消息传递无限循环状态检查工作进程 zeromq 任务分发管道模式

确保ZeroMQ中的工作进程总是正常终止

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