CCS 需要多久关闭一次连接才能执行负载平衡？

Question

我有一个客户端 XMPP，但我从未收到过 CONNECTION_DRAINING 消息，所以我有这个问题， CCS 需要多久关闭一次连接才能执行负载平衡？

这是我验证是否收到 CONNECTION_DRAINING 消息的代码的一部分

............................... more code

def message_callback(session, message):  
    global unacked_messages_quota

    gcmData = message.getTags('data:gcm')
    if gcmData:
        print "alert, the connection is being drained and will be closed soon !!!!!!!!!!!!!"                    
    gcm = message.getTags('gcm')
    if gcm:
        gcm_json = gcm[0].getData()
        msg = json.loads(gcm_json)          
    if not msg.has_key('message_type'):     
      # Acknowledge the incoming message immediately.                   
      send({'to': msg['from'],
            'message_type': 'ack',
            'message_id': msg['message_id']})
.......................................................... more code

我已经阅读了 https://developers.google.com/cloud-messaging/ccs

的文档

特别是这部分

Periodically, CCS needs to close down a connection to perform load balancing. Before it closes the connection, CCS sends a CONNECTION_DRAINING message to indicate that the connection is being drained and will be closed soon. "Draining" refers to shutting off the flow of messages coming into a connection, but allowing whatever is already in the pipeline to continue. When you receive a CONNECTION_DRAINING message, you should immediately begin sending messages to another CCS connection, opening a new connection if necessary. You should, however, keep the original connection open and continue receiving messages that may come over the connection (and ACKing them)—CCS handles initiating a connection close when it is ready.

The CONNECTION_DRAINING message looks like this:

<message>
  <data:gcm xmlns:data="google:mobile:data">
  {
    "message_type":"control"
    "control_type":"CONNECTION_DRAINING"
  }
  </data:gcm>
</message>

Answer 1

通常至少每周一次，但根据负载情况可以更频繁。