Scrapy怎样同时运行多个爬虫？

　　默认情况下，当你运行 scrapy crawl 命令的时候，scrapy只能在单个进程里面运行一个爬虫。然后Scrapy运行方式除了采用命令行式的运行方式以外还可以使用API的方式来运行爬虫，而采用API的方式运行的爬虫是支持运行多个爬虫的。

　　下面的案例是运行多个爬虫：

import scrapy
from scrapy.crawler import CrawlerProcess

class MySpider1(scrapy.Spider):
    # Your first spider definition
    ...

class MySpider2(scrapy.Spider):
    # Your second spider definition
    ...

process = CrawlerProcess() # 初始化事件循环
process.crawl(MySpider1) # 将爬虫类方式事件循环
process.crawl(MySpider2) # 将爬虫类方式事件循环
process.start() # the script will block here until all crawling jobs are finished

　　此外采用 CrawlerRunner 也是可行的：

import scrapy
from twisted.internet import reactor
from scrapy.crawler import CrawlerRunner
from scrapy.utils.log import configure_logging

class MySpider1(scrapy.Spider):
    # Your first spider definition
    ...

class MySpider2(scrapy.Spider):
    # Your second spider definition
    ...

configure_logging()
runner = CrawlerRunner()
runner.crawl(MySpider1)
runner.crawl(MySpider2)
d = runner.join()
d.addBoth(lambda _: reactor.stop())

reactor.run() # the script will block here until all crawling jobs are finished

　　deferreds的方式来运行：

from twisted.internet import reactor, defer
from scrapy.crawler import CrawlerRunner
from scrapy.utils.log import configure_logging

class MySpider1(scrapy.Spider):
    # Your first spider definition
    ...

class MySpider2(scrapy.Spider):
    # Your second spider definition
    ...

configure_logging()
runner = CrawlerRunner()

@defer.inlineCallbacks
def crawl():
    yield runner.crawl(MySpider1)
    yield runner.crawl(MySpider2)
    reactor.stop()

crawl()
reactor.run() # the script will block here until the last crawl call is finished

　　更多细节参考：

       Scrapy文档