Poloniex push api: Stop sending data of channel 1002

I use python to get the real time data from wss://api2.poloniex.com:443 and it's work.
But sometime server will stop sending the data of the channel 1002 (tick real time information) but there is still heartbeat [1010]
and here is my code

from threading import Thread

import websocket

'''
Message format
[
    1002,                             Channel
    null,                             Unknown
    [
        121,                          CurrencyPairID
        "10777.56054438",             Last
        "10800.00000000",             lowestAsk
        "10789.20000001",             highestBid
        "-0.00860373",                percentChange
        "72542984.79776118",          baseVolume
        "6792.60163706",              quoteVolume
        0,                            isForzen
        "11400.00000000",             high24hr
        "9880.00000009"               low24hr
    ]
]
'''


class Ticker:



    def on_open(self, ws):
        ws.send(json.dumps({'command': 'subscribe', 'channel': 1002}))

    def on_message(self, ws, message):
        message = json.loads(message)
        print(message)

    def on_close(self, ws ):
        self.isReady = False
        logging.warning('Poloniex Ticker----------------------------CLOSE WebSocket-----------------------')
        logging.warning('Close Time : ' + timestampToDate(int(time.mktime(time.localtime())), True))
        time.sleep(1)
        logging.info('Restart Poloniex Ticker Socket')
        self.start()

    def start(self):
        logging.info('poloniex tick start')
        self.ws = websocket.WebSocketApp('wss://api2.poloniex.com:443', on_open=self.on_open, on_message=self.on_message,
                                         on_close=self.on_close, on_error=self.on_error)
        self.thread = Thread(target=self.ws.run_forever)
        self.thread.start() 

When the program is work is like that

When the server stop sending data of channel 1002

Any idea?

It seems that Poloniex's websocket is unstable It will stop sending data to Client for 2 min when server is busy, even you using a web browser