Python 协程

手动协程操作：

# pip install gevent
from greenlet import greenlet

def test():
    print('He ')
    gr2.switch()  # 切换到test2
    print('a ')
    gr2.switch()

def test2():
    print('is ')
    gr1.switch()
    print('student.')

gr1 = greenlet(test)   # 创建一个协程
gr2 = greenlet(test2)
gr1.switch()    # 切换到gr1，也就是运行它

2. 自动协程，遇到I/O自动切换

import gevent
from gevent import monkey; monkey.patch_all()   # 导入monkey，给所有支持的模块打上补丁，变成非阻塞模块，也就是使其能够进行协程操作

def test1(n):
    print("I'm doing my homework.")
    gevent.sleep(n)          # 模拟I/O操作，gevent自动切换
    print('Keep doing my homework.')

def test2(n):
    print("I have no time to watch TV.")
    gevent.sleep(n)
    print('Stop thinking!')

def test3():
    print("Life is hard.")

# 等待 greenlets 全部结束
gevent.joinall([
    gevent.spawn(test1,3),  # 创建一个新的greeenlet对象，并规划它去执行 test1(3)
    gevent.spawn(test2,1),
    gevent.spawn(test3),
])

结果：

I'm doing my homework.
I have no time to watch TV.
Life is hard.
Stop thinking!
Keep doing my homework.

3. socket 协程实例：

服务器：

import socket
import gevent
from gevent import monkey
monkey.patch_all()    # 打补丁，让所有支持的模块变成非阻塞的方法

def server(ip,port):
    s = socket.socket()   # 生成socket对象
    s.bind((ip, port))    # 绑定ip和端口
    s.listen()            # 设置监听
    while True:
        cli, addr = s.accept()              # 等待连接
        gevent.spawn(handle_request, cli)   # 对每一个连接，使用协程的方法生成greenlet

def handle_request(conn):
    try:
        while True:
            data = conn.recv(1024)    # 接收数据
            print("recv:", data)
            new = 'Hello '+ data.decode().title()
            conn.send(new.encode('utf8'))           # 返回数据
            if not data:
                conn.shutdown(socket.SHUT_WR)
    except Exception as e:
        print(e)
    finally:
        conn.close()

if __name__ == '__main__':
    server('localhost',9999)

客户端：

import socket

client = socket.socket()
client.connect(('localhost',9999))

while True:
    con = input('>>>:').strip()
    if len(con) ==0: continue
    client.send(con.encode('utf-8'))
    data = client.recv(1024)
    print(data.decode())

client.close()