在for循环中运行多个蜘蛛

Question

I try to instantiate multiple spiders. The first one works fine, but the second one gives me an error: ReactorNotRestartable.

feeds = {
    'nasa': {
        'name': 'nasa',
        'url': 'https://www.nasa.gov/rss/dyn/breaking_news.rss',
        'start_urls': ['https://www.nasa.gov/rss/dyn/breaking_news.rss']
    },
    'xkcd': {
        'name': 'xkcd',
        'url': 'http://xkcd.com/rss.xml',
        'start_urls': ['http://xkcd.com/rss.xml']
    }    
}

With the items above, I try to run two spiders in a loop, like this:

from scrapy.crawler import CrawlerProcess
from scrapy.spiders import XMLFeedSpider

class MySpider(XMLFeedSpider):

    name = None

    def __init__(self, **kwargs):

        this_feed = feeds[self.name]
        self.start_urls = this_feed.get('start_urls')
        self.iterator = 'iternodes'
        self.itertag = 'items'
        super(MySpider, self).__init__(**kwargs)

def parse_node(self, response, node):
    pass


def start_crawler():
    process = CrawlerProcess({
        'USER_AGENT': CONFIG['USER_AGENT'],
        'DOWNLOAD_HANDLERS': {'s3': None} # boto issues
    })

    for feed_name in feeds.keys():
        MySpider.name = feed_name
        process.crawl(MySpider)
        process.start() 

The exception for the second loop looks like this, spider opened, but then:

...
2015-11-22 00:00:00 [scrapy] INFO: Spider opened
2015-11-22 00:00:00 [scrapy] INFO: Crawled 0 pages (at 0 pages/min), scraped 0 items (at 0 items/min)
2015-11-22 00:00:00 [scrapy] DEBUG: Telnet console listening on 127.0.0.1:6023
2015-11-21 23:54:05 [scrapy] DEBUG: Telnet console listening on 127.0.0.1:6023
Traceback (most recent call last):
  File "env/bin/start_crawler", line 9, in <module>
    load_entry_point('feed-crawler==0.0.1', 'console_scripts', 'start_crawler')()
  File "/Users/bling/py-feeds-crawler/feed_crawler/crawl.py", line 51, in start_crawler
    process.start() # the script will block here until the crawling is finished
  File "/Users/bling/py-feeds-crawler/env/lib/python2.7/site-packages/scrapy/crawler.py", line 251, in start
    reactor.run(installSignalHandlers=False)  # blocking call
  File "/usr/local/lib/python2.7/site-packages/twisted/internet/base.py", line 1193, in run
    self.startRunning(installSignalHandlers=installSignalHandlers)
  File "/usr/local/lib/python2.7/site-packages/twisted/internet/base.py", line 1173, in startRunning
    ReactorBase.startRunning(self)
  File "/usr/local/lib/python2.7/site-packages/twisted/internet/base.py", line 684, in startRunning
    raise error.ReactorNotRestartable()
twisted.internet.error.ReactorNotRestartable

Do I have to invalidate the first MySpider or what am I doing wrong and need to change that it works. Thanks in advance.

Answer 1

looks like you have to instantiate a process per spider, try:

def start_crawler():      

    for feed_name in feeds.keys():
        process = CrawlerProcess({
            'USER_AGENT': CONFIG['USER_AGENT'],
            'DOWNLOAD_HANDLERS': {'s3': None} # boto issues
        })
        MySpider.name = feed_name
        process.crawl(MySpider)
        process.start() 

Answer 2

Solution is to collect the spiders in the loop and start process just once at the end. My guess, it has something to do with the Reactor allocation / deallocation.

def start_crawler():

    process = CrawlerProcess({
        'USER_AGENT': CONFIG['USER_AGENT'],
        'DOWNLOAD_HANDLERS': {'s3': None} # disable for issues with boto
    })

    for feed_name in CONFIG['Feeds'].keys():
        MySpider.name = feed_name
        process.crawl(MySpider)

    process.start()

Thanks @eLRuLL for your answer it inspired me to find this solution.

Answer 3

You can send params in the crawl and use them in parsing process.

class MySpider(XMLFeedSpider):
    def __init__(self, name, **kwargs):
        super(MySpider, self).__init__(**kwargs)

        self.name = name


def start_crawler():      
    process = CrawlerProcess({
        'USER_AGENT': CONFIG['USER_AGENT'],
        'DOWNLOAD_HANDLERS': {'s3': None} # boto issues
    })

    for feed_name in feeds.keys():
        process.crawl(MySpider, feed_name)

    process.start()