title: Flask-SocketIO cannot receive event from redis message_queue
body: <p>I am trying to send and receive events from a client (running on an external process)  to Flask-SocketIO server using redis as message_queue but the server doesn't receive any event the client emit.</p>
  
  <p>The server:</p>
  
  <pre class="lang-py prettyprint-override"><code>from flask_socketio import SocketIO, Namespace
  from flask import Flask
  
  
  class MyNamespace(Namespace):
     def on_my_event(self, data):
          print('Data received:', data)
  
  app = Flask(__name__)
  app.config['SECRET_KEY'] = 'secret!'
  socketio = SocketIO()
  socketio.on_namespace(MyNamespace('/my_namespace'))
  socketio.init_app(app, message_queue='redis://127.0.0.1:6379')
  
  if __name__ == '__main__':
      app.run()
  </code></pre>
  
  <p>The client:</p>
  
  <pre class="lang-py prettyprint-override"><code>from flask_socketio import SocketIO
  import time
  
  socketio = SocketIO(message_queue='redis://127.0.0.1:6379')
  
  
  def test():
      count = 0
      while True:
          print('Data:', count)
          socketio.emit('my_event', {'data': count},
                         namespace='/my_namespace',
                         broadcast=True)
          count += 1
          time.sleep(2)
  
  
  if __name__ == '__main__':
      test()
  </code></pre>
  
  <p>Redis server is running in a docker container with docker-compose:</p>
  
  <pre><code>version: '3.3'
  
  services:
      redis:
          build: ./redis
          volumes: 
            - ./redis/data:/data
          expose: 
            - 6379
          ports: 
            - 6379:6379
  </code></pre>
  
  <p>The <code>redis-cli monitor</code> output:</p>
  
  <pre><code>1576594467.587035 [0 172.22.0.1:38534] "PUBLISH" "flask-socketio" "\x80\x03}q\x00(X\x06\x00\x00\x00methodq\x01X\x04\x00\x00\x00emitq\x02X\x04\x00\x00\x00dataq\x03}q\x04h\x03K\x83sX\b\x00\x00\x00callbackq\x05NX\x04\x00\x00\x00roomq\x06NX\b\x00\x00\x00skip_sidq\aNX\x05\x00\x00\x00eventq\bX\b\x00\x00\x00my_eventq\tX\t\x00\x00\x00namespaceq\nX\r\x00\x00\x00/my_namespaceq\x0bX\a\x00\x00\x00host_idq\x0cX \x00\x00\x0053331c21d78649cea28d1ad9e1010179q\ru."
  1576594469.590627 [0 172.22.0.1:38534] "PUBLISH" "flask-socketio" "\x80\x03}q\x00(X\x06\x00\x00\x00methodq\x01X\x04\x00\x00\x00emitq\x02X\x04\x00\x00\x00dataq\x03}q\x04h\x03K\x84sX\b\x00\x00\x00callbackq\x05NX\x04\x00\x00\x00roomq\x06NX\b\x00\x00\x00skip_sidq\aNX\x05\x00\x00\x00eventq\bX\b\x00\x00\x00my_eventq\tX\t\x00\x00\x00namespaceq\nX\r\x00\x00\x00/my_namespaceq\x0bX\a\x00\x00\x00host_idq\x0cX \x00\x00\x0053331c21d78649cea28d1ad9e1010179q\ru."
  1576594471.593944 [0 172.22.0.1:38534] "PUBLISH" "flask-socketio" "\x80\x03}q\x00(X\x06\x00\x00\x00methodq\x01X\x04\x00\x00\x00emitq\x02X\x04\x00\x00\x00dataq\x03}q\x04h\x03K\x85sX\b\x00\x00\x00callbackq\x05NX\x04\x00\x00\x00roomq\x06NX\b\x00\x00\x00skip_sidq\aNX\x05\x00\x00\x00eventq\bX\b\x00\x00\x00my_eventq\tX\t\x00\x00\x00namespaceq\nX\r\x00\x00\x00/my_namespaceq\x0bX\a\x00\x00\x00host_idq\x0cX \x00\x00\x0053331c21d78649cea28d1ad9e1010179q\ru."
  </code></pre>
  
  <p>The server does not print out any thing, please help me!</p>