协程

1、使用 greenlet 实现协程

from greenlet import greenlet

def eat():
    print('eating start')
    g2.switch()
    print('eating end')
    g2.switch()


def play():
    print('playing start')
    g1.switch()
    print('playing end')
    g1.switch()


g1 = greenlet(eat)
g2 = greenlet(play)
g1.switch()

执行效果：

eating start
playing start
eating end
playing end

2 、使用 gevent 实现协程。注意第一句

from gevent import monkey; monkey.patch_all() 要放在其它导入模块的上面，将把下面导入模块的阻塞事件打包处理。

from gevent import monkey; monkey.patch_all()

import time
import gevent

def eat():
    print('eating start')
    time.sleep(1)
    print('eating end')

def play():
    print('playing start')
    time.sleep(1)
    print('playing end')

g1 = gevent.spawn(eat)
g2 = gevent.spawn(play)
g1.join()
g2.join()

输出同例子1

3、协程的效果

from gevent import monkey; monkey.patch_all()

import time
import gevent

def task():
    time.sleep(1)
    print('doing job...')

def sync1():
    for i in range(10):
        task()


def async1():
    g_list=[]
    for i in range(10):
        g = gevent.spawn(task)
        g_list.append(g)
    gevent.joinall(g_list)

#sync1()
async1()

3、利用协程爬取一些信息

from gevent import monkey;monkey.patch_all()
import gevent
from urllib.request import urlopen


def get_url(url1):
    res = urlopen(url1)
    html = res.read().decode('utf-8')
    return len(html)


url_list = ['http://www.baidu.com',
            'http://www.taobao.com',
            'http://www.cnblogs.com',
            'http://www.sina.com.cn',
            'http://www.sohu.com']

g_list = []
for u in url_list:
    g_list.append(gevent.spawn(get_url,u))

gevent.joinall(g_list)

for g in g_list:
    print(g.value, end=' ')

4、协程的TCP server

from gevent import monkey;monkey.patch_all()
import socket
import gevent

sk = socket.socket()
sk.bind(('127.0.0.1', 8090))
sk.listen()


def chat(conn):
    conn.send(b'hello')
    msg = conn.recv(1024).decode('utf-8')
    print(msg)


while True:
    conn, addr = sk.accept()
    gevent.spawn(chat, conn)

可以实现多任务并发了。

Python 学习笔记：协程

协程

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