python 协程

协程

协程就是一种用户态内的上下文切换技术.

 

1.使用gevent实现协程, gevent.spawn()调用函数,  gevent.sleep(1) 模拟阻塞,实现切换.

 1 import gevent
 2 import time
 3 
 4 
 5 def foo():
 6     print('running in foo',time.ctime())
 7     gevent.sleep(1)
 8     print('Explicit context switch to foo again',time.ctime())
 9 
10 
11 def bar():
12     print('running in foo', time.ctime())
13     gevent.sleep(2)
14     print('EIxplicit context switch to foo again', time.ctime())
15 
16 gevent.joinall([
17     gevent.spawn(foo),
18     gevent.spawn(bar)
19 ])
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 2.协程可以实现高并发,且占用的资源比进程和线程少. 

 1 #!/usr/bin/env python3
 2 #  -*- coding=utf-8 -*-
 3 from gevent import monkey
 4 import gevent
 5 monkey.patch_all()  #刷新
 6 from urllib.request import urlopen
 7 import time
 8 
 9 def f(url):
10     print('get:%s'%url)
11     resp=urlopen(url)
12     data=resp.read()
13     print('%d bytes received from %s .' %(len(data),url))
14 
15 l=['http://www.xiaohuar.com/hua/','http://www.zhihu.com/question/21653286','http://news.dahe.cn/2016/10-12/107590869.html']
16 start=time.time()
17 
18 #协程方式
19 gevent.joinall([
20     gevent.spawn(f,'http://www.xiaohuar.com/hua/'),
21     gevent.spawn(f,'http://www.zhihu.com/question/21653286'),
22     gevent.spawn(f,'http://news.dahe.cn/2016/10-12/107590869.html')
23 ])
24 
25 #普通方式
26 # for url in l:
27 #     f(url)
28 
29 print(time.time()-start)
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posted @ 2016-10-12 16:39  noube  阅读(155)  评论(0)  编辑  收藏  举报