class StartRequestsCountMiddleware(object):
    start_urls = {}

def process_start_requests(self, start_requests, spider):
    for i, request in enumerate(start_requests):
        self.start_urls[i] = request.url
request.meta.update(start_request_index=i)
yield request

def process_spider_output(self, response, result, spider):
    for output in result:
        pass
Сколько элементов было извлечено на start_url