Ccxt: Fetch_ohlcv (symbol,'1m') of okex timeout

PROBLIEM：
I run about 30 minutes later, the problem of time out, is the question of exchange, or the problem of ccxt, how to solve it.

• OS: win10
• Programming Language version: python 3.6
• CCXT version: ccxt-1.11.137
• Exchange: okex
• Method: exchange.fetch_ohlcv(self.symbol, '1m')

CODE：

 def get_close_prices(self):
        close_prices = []
        bar_data = np.array(self.exchange.fetch_ohlcv(symbol, '1m'))
        for element in bar_data:
            close_prices.append(float(element[4]))
        return close_prices

if __name__ == '__main__':
while true:
        close_prices = self.get_close_prices()
        time.sleep(1 * 60)

ERROR：

File "E:/work/test/test.py", line 44, in handle_bar
close_prices = np.array(self.get_close_prices())
File "E:/work/test/test.py", line 24, in get_close_prices
bar_data = np.array(self.exchange.fetch_ohlcv(self.symbol, '1m'))
File "E:\sorfware\anaconda3.5\lib\site-packages\ccxt\okcoinusd.py", line 348, in fetch_ohlcv
response = getattr(self, method)(self.extend(request, params))
File "E:\sorfware\anaconda3.5\lib\site-packages\ccxt\base\exchange.py", line 298, in request
return self.fetch2(path, api, method, params, headers, body)
File "E:\sorfware\anaconda3.5\lib\site-packages\ccxt\base\exchange.py", line 295, in fetch2
return self.fetch(request['url'], request['method'], request['headers'], request['body'])
File "E:\sorfware\anaconda3.5\lib\site-packages\ccxt\base\exchange.py", line 359, in fetch
self.raise_error(RequestTimeout, method, url, e)
File "E:\sorfware\anaconda3.5\lib\site-packages\ccxt\base\exchange.py", line 280, in raise_error
raise exception_type(output)
ccxt.base.errors.RequestTimeout: okex GET https://www.okex.com/api/v1/kline.do?symbol=bch_btc&type=1min&since=1521547087487 HTTPSConnectionPool(host='www.okex.com', port=443): Read timed out. (read timeout=10)