Question

使用 REQ-REP 模式，我尝试使用poll请求多个clients超时，以便server检测到它无法使用收到来自第一个client的消息，该消息将超时并转到下一个client。

但似乎在初始超时后，它无法将下一条消息发送到第二个client。

我在zmq.error.ZMQError: Operation cannot be accomplished in current state的{{1}}行收到此错误socket.send_string("Sensor Data")。

完整输出：

server

服务器：

Connecting to machine...
Successfully connected to machine 127.0.0.1:9999
Successfully connected to machine 127.0.0.1:9998
Sending request  0 ...
Machine did not respond
Sending request  1 ...
Traceback (most recent call last):
  File "C:\Users\tobiw\Documents\Python\Raspberry Pi\zmq\REQrep\testSIMPLEpoll.py", line 16, in <module>
    socket.send_string("Sensor Data")
  File "C:\Users\tobiw\AppData\Local\Programs\Python\Python36-32\lib\site-packages\pyzmq-17.0.0b3-py3.6-win32.egg\zmq\sugar\socket.py", line 541, in send_string
    return self.send(u.encode(encoding), flags=flags, copy=copy, **kwargs)
  File "C:\Users\tobiw\AppData\Local\Programs\Python\Python36-32\lib\site-packages\pyzmq-17.0.0b3-py3.6-win32.egg\zmq\sugar\socket.py", line 384, in send
    return super(Socket, self).send(data, flags=flags, copy=copy, track=track)
  File "zmq/backend/cython/socket.pyx", line 727, in zmq.backend.cython.socket.Socket.send
  File "zmq/backend/cython/socket.pyx", line 771, in zmq.backend.cython.socket.Socket.send
  File "zmq/backend/cython/socket.pyx", line 249, in zmq.backend.cython.socket._send_copy
  File "zmq/backend/cython/socket.pyx", line 244, in zmq.backend.cython.socket._send_copy
  File "zmq/backend/cython/checkrc.pxd", line 25, in zmq.backend.cython.checkrc._check_rc
    raise ZMQError(errno)
zmq.error.ZMQError: Operation cannot be accomplished in current state
[Finished in 5.3s with exit code 1]

客户端：

import zmq
import json

ports = ["127.0.0.1:9999", "127.0.0.1:9998"]

context = zmq.Context()
print("Connecting to machine...")
socket = context.socket(zmq.REQ)
socket.setsockopt(zmq.LINGER, 0)
for port in ports:
    socket.connect("tcp://%s" % port)
    print("Successfully connected to machine %s" % port)

for request in range(len(ports)):
    print("Sending request ", request, "...")
    socket.send_string("Sensor Data")  # <-- error occurs here

    # use poll for timeouts:
    poller = zmq.Poller()
    poller.register(socket, zmq.POLLIN)

    socks = dict(poller.poll(5 * 1000))

    if socket in socks:
        try:
            msg_json = socket.recv()
            sens = json.loads(msg_json)
            response = "Sensor: %s :: Data: %s :: Client: %s" % (sens['sensor'], sens['data'], sens['client'])
            print("Received reply ", request, "[", response, "]")
        except IOError:
            print("Could not connect to machine")
    else:
        print("Machine did not respond")

如果import zmq import time import json port = "9998" # multiple similar clients but just with different ports context = zmq.Context() socket = context.socket(zmq.REP) socket.bind("tcp://*:%s" % port) while True: # Wait for next request from server message = str(socket.recv(), "utf-8") print("Received request: ", message) time.sleep(1) msgDict = { 'sensor': "6", 'data': "123456789", 'client': "9876", } msg_json = json.dumps(msgDict) socket.send_string(msg_json)能够收到来自第一个server的消息，则第二个client到第二个send将正常工作，但如果{{1} 不能够从第一个client接收消息，然后再现错误。

Answer 1

最重要的是， REQ-REP 模式中的zmq.error.ZMQError: Operation cannot be accomplished in current state表示send -> recv -> send -> recv的顺序不合规。对于我的情况，由于for-loop中的接收投票，在 REQ服务器方面没有最终recv超时。当方法循环返回时，它再次转到send，结果为send -> recv -> send -> timeout -> send。双send场景是非法的。

我做了什么来纠正它：我从 REQ-REP 模式切换到 DEALER-REP 模式。这为我提供了一个可以与多个 REP 客户端通信的异步服务器。

client保持不变，对于感兴趣的人来说，这是新的server：

服务器：

import zmq import json ports = ["127.0.0.1:9999", "127.0.0.1:9998"] context = zmq.Context() print("Connecting to machine...") socket = context.socket(zmq.DEALER) socket.setsockopt(zmq.LINGER, 0) for port in ports: socket.connect("tcp://%s" % port) print("Successfully connected to machine %s" % port) for request in range(len(ports)): print("Sending request ", request, "...") socket.send_string("", zmq.SNDMORE) # delimiter socket.send_string("Sensor Data") # actual message # use poll for timeouts: poller = zmq.Poller() poller.register(socket, zmq.POLLIN) socks = dict(poller.poll(5 * 1000)) if socket in socks: try: socket.recv() # discard delimiter msg_json = socket.recv() # actual message sens = json.loads(msg_json) response = "Sensor: %s :: Data: %s :: Client: %s" % (sens['sensor'], sens['data'], sens['client']) print("Received reply ", request, "[", response, "]") except IOError: print("Could not connect to machine") else: print("Machine did not respond")

PYZMQ REQ-REP具有轮询的多个客户端ZMQError

1 个答案: