import requests，pymongo, time
    from bs4 import BeautifulSoup
    from multiprocessing import Pool
    from channel_extact  import channel_list
    from pages_parsing   import get_links_from
    
    client = pymongo.MongoClient('localhost', 27017)
    gan_ji = client['ganji']
    url_list = gan_ji['url_list']
    iterm_info = gan_ji['iterm_info']
    
    db_urls = [iterm['url'] for iterm in url_list.find()]#在url_list中找到全部的iterm,iterm['url']是url
    index_urls = [iterm['url'] for iterm in iterm_info.find()]
    x = set(db_urls)
    y = set(index_urls)
    rest_of_urls = x-y
    if __name__ == '__main__':
        pool = Pool()
        # pool = Pool(processes=6)
        pool.map(get_all_links_from,channel_list.split())#參數(shù)一是函數(shù)，接受參數(shù)二

Python set的操作
多進(jìn)程multiprocessing中進(jìn)程池Pool（）以及方法map的用法
更為詳細(xì)的有關(guān)multiprocessing的介紹