# When you run the Scrapy crawler from a program, the code blocks until the Scrapy crawler is finished. This is due to how Twisted (the underlying asynchronous network library) works. This prevents using the Scrapy crawler from scripts or other code.
# 
# To circumvent this issue you can run the Scrapy crawler in a thread with this code.
# 
# Keep in mind that this code is mainly for illustrative purposes and far from production ready.
# 
# Also the code was only tested with Scrapy 0.8, and will probably need some adjustments for newer versions (since the core API isn't stable yet), but you get the idea.

"""
Code to run Scrapy crawler in a thread - works on Scrapy 0.8
"""

import threading, Queue

from twisted.internet import reactor

from scrapy.xlib.pydispatch import dispatcher
from scrapy.core.manager import scrapymanager
from scrapy.core.engine import scrapyengine
from scrapy.core import signals

class CrawlerThread(threading.Thread):

    def __init__(self): 
        threading.Thread.__init__(self)
        self.running = False

    def run(self):
        self.running = True
        scrapymanager.configure(control_reactor=False)
        scrapymanager.start()
        reactor.run(installSignalHandlers=False)

    def crawl(self, *args):
        if not self.running:
            raise RuntimeError("CrawlerThread not running")
        self._call_and_block_until_signal(signals.spider_closed, \
            scrapymanager.crawl, *args)

    def stop(self):
        reactor.callFromThread(scrapyengine.stop)

    def _call_and_block_until_signal(self, signal, f, *a, **kw):
        q = Queue.Queue()
        def unblock():
            q.put(None)
        dispatcher.connect(unblock, signal=signal)
        reactor.callFromThread(f, *a, **kw)
        q.get()


# Usage example below:

import os
os.environ.setdefault('SCRAPY_SETTINGS_MODULE', 'myproject.settings')

from scrapy.xlib.pydispatch import dispatcher
from scrapy.core import signals
from scrapy.conf import settings
from scrapy.crawler import CrawlerThread

settings.overrides['LOG_ENABLED'] = False # avoid log noise

def item_passed(item):
    print "Just scraped item:", item

dispatcher.connect(item_passed, signal=signals.item_passed)

crawler = CrawlerThread()
print "Starting crawler thread..."
crawler.start()
print "Crawling somedomain.com...."
crawler.crawl('somedomain.com) # blocking call
print "Crawling anotherdomain.com..."
crawler.crawl('anotherdomain.com') # blocking call
print "Stopping crawler thread..."
crawler.stop()

# Snippet imported from snippets.scrapy.org (which no longer works)
# author: pablo
# date  : Aug 11, 2010

Run Scrapy crawler in a thread

Python