脚本中的Scrapy爬行总是在抓取后阻止脚本执行

Question

我按照本指南http://doc.scrapy.org/en/0.16/topics/practices.html#run-scrapy-from-a-script从我的脚本运行scrapy。 这是我的脚本的一部分：

    crawler = Crawler(Settings(settings))
    crawler.configure()
    spider = crawler.spiders.create(spider_name)
    crawler.crawl(spider)
    crawler.start()
    log.start()
    reactor.run()
    print "It can't be printed out!"

它应该工作：访问页面，刮取所需信息并存储我告诉它的输出json（通过FEED_URI）。 但是当蜘蛛完成他的工作时（我可以通过输出json中的数字看到它）我的脚本执行不会恢复。 可能它不是scrapy问题。 并且应该在扭曲的反应堆中找到答案。 我怎么能释放线程执行？

Answer 1

当蜘蛛完成时，你需要停止反应堆。 您可以通过监听spider_closed信号来完成此spider_closed ：

from twisted.internet import reactor

from scrapy import log, signals
from scrapy.crawler import Crawler
from scrapy.settings import Settings
from scrapy.xlib.pydispatch import dispatcher

from testspiders.spiders.followall import FollowAllSpider

def stop_reactor():
    reactor.stop()

dispatcher.connect(stop_reactor, signal=signals.spider_closed)
spider = FollowAllSpider(domain='scrapinghub.com')
crawler = Crawler(Settings())
crawler.configure()
crawler.crawl(spider)
crawler.start()
log.start()
log.msg('Running reactor...')
reactor.run()  # the script will block here until the spider is closed
log.msg('Reactor stopped.')

命令行日志输出可能如下所示：

stav@maia:/srv/scrapy/testspiders$ ./api
2013-02-10 14:49:38-0600 [scrapy] INFO: Running reactor...
2013-02-10 14:49:47-0600 [followall] INFO: Closing spider (finished)
2013-02-10 14:49:47-0600 [followall] INFO: Dumping Scrapy stats:
    {'downloader/request_bytes': 23934,...}
2013-02-10 14:49:47-0600 [followall] INFO: Spider closed (finished)
2013-02-10 14:49:47-0600 [scrapy] INFO: Reactor stopped.
stav@maia:/srv/scrapy/testspiders$

Answer 2

在scrapy 0.19.x中你应该这样做：

from twisted.internet import reactor
from scrapy.crawler import Crawler
from scrapy import log, signals
from testspiders.spiders.followall import FollowAllSpider
from scrapy.utils.project import get_project_settings

spider = FollowAllSpider(domain='scrapinghub.com')
settings = get_project_settings()
crawler = Crawler(settings)
crawler.signals.connect(reactor.stop, signal=signals.spider_closed)
crawler.configure()
crawler.crawl(spider)
crawler.start()
log.start()
reactor.run() # the script will block here until the spider_closed signal was sent

请注意这些行

settings = get_project_settings()
crawler = Crawler(settings)

如果没有它，您的蜘蛛将不会使用您的设置，也不会保存项目。 花了一些时间来弄清楚为什么文档中的示例没有保存我的项目。 我发送了一个pull请求来修复doc示例。

另一种方法是直接从您的脚本调用命令

from scrapy import cmdline
cmdline.execute("scrapy crawl followall".split())  #followall is the spider's name