xpath的多线程爬虫

#encoding=utf-8'''pool = Pool(4) cpu的核数为4核results = pool.map(爬取函数，网址列表)'''from multiprocessing.dummy import Pool as ThreadPoolimport requestsimport timedef getsource(url):    html = requests.get(url)urls = []for i in range(1,21):    newpage = 'http://tieba.baidu.com/p/3522395718?pn=' + str(i)    urls.append(newpage)time1 = time.time()for i in urls:    print i    getsource(i)time2 = time.time()print u'单线程耗时：' + str(time2-time1)pool = ThreadPool(4)time3 = time.time()results = pool.map(getsource, urls)pool.close()pool.join()time4 = time.time()print u'并行耗时：' + str(time4-time3)

输出：

单线程耗时：12.0818030834

并行耗时：3.58480286598