ZeroMQ 推送套接字导致客户端在没有进程正在侦听时终止 [英] ZeroMQ push socket causes client to not terminate when no process is listening

问题描述

我刚刚开始使用 ZeroMQ，我遇到了一个无法正常终止的客户端的问题.特别是我有一个客户端，它可以在没有接收器服务器正在侦听时推送"数据，并且在 python 代码完成后似乎使进程挂起.我假设有一些后台线程需要清理 - 请告诉我如何或指向文档.

I'm just starting to mess with ZeroMQ and I have a problem with a client that doesn't terminate normally. In particular I have a client that may "push" data when no sink server is listening and that seems to make the process hang after the python code has finished. I assume there is some background thread that needs to be cleaned up -- please tell me how or point to documentation.

这是相关的代码段.如果我在没有侦听器的情况下运行进程并取消注释self.push"行，进程会挂起

Here is the relevant piece of code. If I run the process with no listener with the "self.push" line uncommented the process hangs

def setup(self):
    print self.name, "connect to sockets"
    ctx = self.ctx = zmq.Context()
    self.pull = ctx.socket(zmq.PULL)
    self.pull.connect(self.ventillatorAddress)
    self.push = ctx.socket(zmq.PUSH)
    self.push.connect(self.sinkAddress)
    self.control = ctx.socket(zmq.SUB)
    self.control.connect(self.publisherAddress)
    self.control.setsockopt(zmq.SUBSCRIBE, "") # get every control message
    self.inbox = ctx.socket(zmq.SUB)
    self.inbox.connect(self.distributorAddress)
    self.inbox.setsockopt(zmq.SUBSCRIBE, self.name) # listen only for messages addressed with name
def start(self):
    print self.name,  "push worker is ready signal"
    # listen for "go" signal
    pollcount = 0
    go = False
    while not go:
        #print "send ready for", self.name
        #self.push.send(self.name+" ready")
        print "listen for 'go'"
        msg = self.recvPoll(self.control)
        if msg is None:
            pollcount += 1
            assert pollcount<10
            print "poll timeout", pollcount
            time.sleep(1)
            continue
        pollcount = 0
        print "recv'd", msg
        assert msg=="go!"
        go = True
    print "go signal received"
    pass

注释行(并且没有侦听器)后，该过程正常完成.我尝试了 context.term() 和 context.destroy() ，但它们似乎没有帮助.

With the line commented (and no listener) the process completes normally. I tried context.term() and context.destroy() and they don't seem to help.

如何清理套接字?或者还有什么线索?提前致谢！

How can I clean up the socket? Or any other clues? Thanks in advance!

推荐答案

这很可能是由于 ZeroMQ 的 linger 功能.引用自 手册页:

This is most probably due to the linger functionality of ZeroMQ. Quoting from the man page:

ZMQ_LINGER 选项应设置指定套接字的延迟时间.延迟周期决定了在使用 zmq_close(3) 关闭套接字后，尚未发送到对等方的未决消息应在内存中停留多长时间，并进一步影响使用 zmq_term(3) 终止套接字上下文.

The ZMQ_LINGER option shall set the linger period for the specified socket. The linger period determines how long pending messages which have yet to be sent to a peer shall linger in memory after a socket is closed with zmq_close(3), and further affects the termination of the socket's context with zmq_term(3).

默认值会导致 ZeroMQ 无限期地等待，直到它能够传递卡住的消息.

The default value causes ZeroMQ to wait indefinitely until it is able to deliver the stuck message.

尝试将 ZMQ_LINGER 套接字选项设置为零或短时间(以毫秒为单位).

Try setting the ZMQ_LINGER socket option to zero or a short time (in milliseconds).

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