mutilprocessing.dummy
multiprocessing.dummy 模块与 multiprocessing 模块的区别： dummy 模块是多线程，而 multiprocessing 是多进程， api 都是通用的。 所有可以很方便将代码在多线程和多进程之间切换
# from multiprocessing import Pool
from multiprocessing.dummy import Pool as ThreadPool
import time
import urllib2
urls = [
'http://www.baidu.com',
'http://home.baidu.com/',
'http://tieba.baidu.com/',
'http://zhidao.baidu.com/',
'http://music.baidu.com/',
'http://image.baidu.com/',
'http://python-china.org/',
'http://python-china.org/node/about',
'http://python-china.org/node/',
'http://python-china.org/account/signin',
'http://python-china.org/account/signup',
'http://www.qq.com',
'http://www.youku.com',
'http://www.tudou.com'
]
start = time.time()
results = map(urllib2.urlopen, urls)
print 'Normal:', time.time() - start
start2 = time.time()
# 开8个 worker，没有参数时默认是 cpu 的核心数
pool = ThreadPool(processes=8)
# 在线程中执行 urllib2.urlopen(url) 并返回执行结果
results2 = pool.map(urllib2.urlopen, urls)
pool.close()
pool.join()
print 'Thread Pool:', time.time() - start2
