有时爬虫会报如下超时错误：

Traceback (most recent call last): File "/opt/pyspider/pyspider/run.py", line 351, in  app.config['fetch'] = lambda x: umsgpack.unpackb(fetcher_rpc.fetch(x).data) File "/usr/lib/python2.7/xmlrpclib.py", line 1233, in __call__ return self.__send(self.__name, args) File "/usr/lib/python2.7/xmlrpclib.py", line 1587, in __request verbose=self.__verbose File "/usr/lib/python2.7/xmlrpclib.py", line 1273, in request return self.single_request(host, handler, request_body, verbose) File "/usr/lib/python2.7/xmlrpclib.py", line 1321, in single_request response.msg, ProtocolError: 

请问有什么好的方法避免？