使用flask-socketIO进行服务器端轮询

Question

我有一个围绕flask-socketIO框架构建的客户端 - 服务器设置。其中一个应用程序是服务器重复轮询数据库，并在更新时让客户端知道。这是我的代码的简单版本：

客户端代码：

function poll(){
    socket.emit('pollForUpdates');
}

socket.on("update",function(msg){
    alert("Recieved update");
});

服务器端代码：

@socketio.on('pollForUpdates')
def pollForUpdates():
    event = threading.Event()
    k = ThreadJob(poll, event, 2)
    k.start()

class ThreadJob(threading.Thread):
    def __init__(self,callback,event,interval):
        '''runs the callback function after interval seconds

        :param callback:  callback function to invoke
        :param event: external event for controlling the update operation
        :param interval: time in seconds after which are required to fire the callback
        :type callback: function
        :type interval: int
        '''
        self.callback = callback
        self.event = event
        self.interval = interval
        super(ThreadJob,self).__init__()

    def run(self):
        while not self.event.wait(self.interval):
            self.callback()


def poll():
    print "Polling at {}".format(datetime.now())
    socketio.emit("update")
    gevent.sleep(0)

客户端无法接收服务器发送的更新。