为什么scrapy-plugins/scrapy-jsonrpc无法获取爬行器的统计数据

from scrapy import signals
from scrapy.crawler import CrawlerProcess
from scrapy.utils.project import get_project_settings

class MySpider:
    def __init__(self):
        self.stats = {}

    @classmethod
    def from_crawler(cls, crawler):
        spider = cls()
        crawler.signals.connect(spider.spider_opened, signal=signals.spider_opened)
        crawler.signals.connect(spider.spider_closed, signal=signals.spider_closed)
        return spider

    def spider_opened(self, spider):
        self.stats['start_time'] = spider.start_time

    def spider_closed(self, spider):
        self.stats['finish_time'] = spider.finish_time
        self.stats['item_scraped_count'] = spider.crawler.stats.get_value('item_scraped_count')
        # 其他统计信息...

    def print_stats(self):
        print("Start time:", self.stats['start_time'])
        print("Finish time:", self.stats['finish_time'])
        print("Item scraped count:", self.stats['item_scraped_count'])
        # 输出其他统计信息...

# 创建爬虫实例
spider = MySpider()

# 创建CrawlerProcess实例
process = CrawlerProcess(get_project_settings())

# 将爬虫实例添加到CrawlerProcess中
process.crawl(spider)

# 启动爬虫
process.start()

# 输出统计信息
spider.print_stats()