#协程，又称为微线程，是一种用户态的轻量级线程

#!usr/bin/env python # -*- coding:utf-8 -*- __author__ = "Samson" #greenlet是协程"手动挡切换" from greenlet import greenlet def test1():     print(12)     t2.switch()#切换到协程t2     print(36)     t2.switch() def test2():     print(48)     t1.switch()     print(60) t1 = greenlet(test1)#启动一个协程 t2 = greenlet(test2) t1.switch()

#!usr/bin/env python # -*- coding:utf-8 -*- __author__ = "Samson" #greenlet是协程"自动挡切换" import gevent def foo():     print("Running in foo")     gevent.sleep(2)#模仿io操作     print("Explicit context switch to foo again") def bar():     print("Explicit精确的 context内容 to bar")     gevent.sleep(1)  # 模仿io操作     print("Implicit context switch back to bar")     gevent.joinall([         gevent.spawn(foo),         gevent.spawn(bar),     ]) 协程之爬虫

#!usr/bin/env python # -*- coding:utf-8 -*- __author__ = "Samson" from urllib import request import gevent,time from gevent import monkey monkey.patch_all()#将当前所有程序io操作单独做上标记，这样才能用协程方式进行爬虫，否则将会是串行的 def f(url):     print("Get: %s" %url)     resp = request.urlopen(url)     data = resp.read()     print("%d bytes received from %s."%(len(data),url)) urls = ["https://www.python.org/",     "https://www.yahoo.com/",     "https://github.com/"] time_start = time.time() for url in urls:     f(url) print("同步cost",time.time()-time_start) async_time_start = time.time() gevent.joinall([     gevent.spawn(f,"https://www.python.org/"),     gevent.spawn(f,"https://www.yahoo.com/"),     gevent.spawn(f,"https://github.com/"), ]) print("协程cost",time.time()-async_time_start)