downloadermiddlewares.py 文件源码

def process_exception(self, request, exception, spider):
        #???????????????????request??????
        #???????????????

        #????????????????????????????????????
        if isinstance(exception, DNSLookupError):           
            self.crawler.signals.send_catch_log(dnslookuperror, spider=spider)

        if isinstance(exception, (TimeoutError, TCPTimedOutError)):         
            self.crawler.signals.send_catch_log(timeouterror, spider=spider)

        return request