python的协程,monkeyPatch

monkey patch 一般指运行时候进行动态替换.

基本上我们使用gevent,会在最开头的地方加入 gevent.monkey.patch_all() ;把标准库中的 thread/socket 等给替换掉.这样我们在后面使用socket的时候它会变成非阻塞的了.而我们却什么也不用做.

一个案列

from gevent import monkey; monkey.patch_all()

import gevent

from urllib import request

def run_task(url):

    print("开始访问 --> %s" % url)

    try:

        response = request.urlopen(url)

        data = response.read()

        print("{} bytes received from {}".forma(len(data), url))

    except Exception:

        print("访问中出错了")

if __name__ == '__main__':

    urls = ['https://baidu.com/', 'https://github.com','https://blog.csdn.net/', 'https://cnblogs.com/lovesKey']

    # 定义协程方法

    greenlets = [gevent.spawn(run_task, url) for url in urls]

    # 添加协程任务，并且启动运行

    gevent.joinall(greenlets)

最快访问结束的会在第一位,最慢的会在最后一位.

输出结果:

Visit --> https://baidu.com/

Visit --> https://github.com

Visit --> https://blog.csdn.net/

Visit --> https://cnblogs.com/lovesKey

154097 bytes received from https://baidu.com/.

26813 bytes received from https://cnblogs.com/lovesKey.

155908 bytes received from https://blog.csdn.net/.

86916 bytes received from https://github.com.