两个蜘蛛完成后如何停止反应器

我有这段代码,当两个蜘蛛完成后,程序仍在运行。

#!C:\Python27\python.exe

from twisted.internet import reactor
from scrapy.crawler import Crawler
from scrapy import log, signals
from carrefour.spiders.tesco import TescoSpider
from carrefour.spiders.carr import CarrSpider
from scrapy.utils.project import get_project_settings
import threading
import time

def tescofcn():
    tescoSpider = TescoSpider()
    settings = get_project_settings()
    crawler = Crawler(settings)
    crawler.configure()
    crawler.crawl(tescoSpider)
    crawler.start()

def carrfcn():
    carrSpider = CarrSpider()
    settings = get_project_settings()
    crawler = Crawler(settings)
    crawler.configure()
    crawler.crawl(carrSpider)
    crawler.start()


t1=threading.Thread(target=tescofcn)
t2=threading.Thread(target=carrfcn)

t1.start()
t2.start()
log.start()
reactor.run()

当我尝试将此插入两个函数时

crawler.signals.connect(reactor.stop, signal=signals.spider_closed)

,对于两种蜘蛛来说,速度更快的蜘蛛和速度较慢的蜘蛛都被终止了,尽管他没有完成。