内容：协程 作用：实现高并发，提高效率
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yield支持下的协程
协程是用户轻量级线程
好处：
1、没有线程切换
2、无需原子操作锁定及同步开销
3、高并发+高扩展+低成本：一个cpu支持上万的协程都没有问题。所以很适合高并发处理
缺点：
1、无法利用多核利用——通过多进程改进
2、一个阻塞，则全部都阻塞了
def consumer(name): print(‘start‘) while True: new_baozi = yield print("[%s]is eating baozi %s" % (name,new_baozi)) def producer(): r = con.__next__() r = con2.__next__() n = 0 while n < 5: n += 1 con.send(n) con2.send(n) print("\033[32;lm[producer]\033[0m is making baozi %s" % n) if __name__ == ‘__main__‘: con = consumer(‘c1‘) con2 = consumer(‘c2‘) p = producer()
执行结果：
start
start
[c1] is eating baozi 1
[c2] is eating baozi 1
[c1] is eating baozi 2
[c2] is eating baozi 2
[c1] is eating baozi 3
[c2] is eating baozi 3
[c1] is eating baozi 4
[c2] is eating baozi 4
[c1] is eating baozi 5
[c2] is eating baozi 5
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gevent下的协程
1、安装
搜索gevent，然后安装
#####greenlet
from greenlet import greenlet def test1(): print(12) gr2.switch() print(34) gr2.switch() def test2(): print(56) gr1.switch() print(78) gr1 = greenlet(test1) # 建立对象 gr2 = greenlet(test2) gr1.switch() # 开始执行
执行结果：
12
56
34
78
######gevent
import gevent def foo(): print(‘running in foo‘) gevent.sleep() print(‘Explicit context switch to foo again‘) def bar(): print(‘Explicit context to bar‘) gevent.sleep() print(‘Implicit context switch back to bar‘) gevent.joinall([ gevent.spawn(foo), gevent.spawn(foo) ])
执行结果：
running in foo
Explicit context to bar
Explicit context switch to foo again
Implicit context switch back to bar
爬网站，可以明显看出串行和并发的效果
from gevent import monkey monkey.patch_all() import gevent from urllib.request import urlopen def f(url): print(‘get:%s‘%url) resp = urlopen(url) data = resp.read() print(‘%dbytesreceviedfrom%s.‘ % (len(data),url)) with open(‘xx.html‘,‘wb‘) as f: f.write(data) gevent.joinall([ gevent.spawn(f,‘https://www.baidu.com‘), #gevent.spawn(f,‘192.168.10.142‘), #gevent.spawn(f,‘192.168.10.142:8080‘) ])
