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.