Python之路【第十七篇】:Python并发编程|协程

时间：2023-03-08 19:18:04

一、协程

协程，又叫微线程，纤程。英文名Coroutine。协程本质上就是一个线程

优点1：协程极高的执行效率。因为子程序切换不是线程切换，而是由程序自身控制，因此，没有线程切换的开销，和多线程比，线程数量越多，协程的性能优势就越来越明显。(简单来说没有切换的消耗)

优点2：不需要多线程的锁机制，因为只有一个线程，也不存在同时写变量冲突，在协程中控制共享资源不加锁，只需要判断状态就好，所以执行效率比多线程高很多。(没有锁的概念)

因为协程是一个线程执行，那怎么利用多核CPU呢？最简单的方法是多进程+协程，既充分利用多核，又充分发挥协程的高效率，可获得极高的性能。

二、yield的简单实现

#_*_ coding:utf-8 _*_

# Author:Simon

# Datetime:2019/9/2 21:07

# Software:PyCharm

import time

import queue

def consumer(name):

    print("--->ready to eat baozi...")

    while True:

        new_baozi = yield

        print("[%s] is eating baozi %s" % (name,new_baozi))

        #time.sleep(1)

def producer():

    r = con.__next__()

    r = con2.__next__()

    n = 0

    while 1:

        time.sleep(1)

        print("\033[32;1m[producer]\033[0m is making baozi %s and %s" %(n,n+1) )

        con.send(n)

        con2.send(n+1)

        n +=2

if __name__ == '__main__':

    con = consumer("c1")

    con2 = consumer("c2")

    p = producer()

三、Greenlet模块

greenlet是一个用C实现的协程模块，相比与python自带的yield，它可以使你在任意函数之间随意切换，而不需把这个函数先声明为generator

#_*_ coding:utf-8 _*_

# Author:Simon

# Datetime:2019/9/2 21:29

# Software:PyCharm

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)

gr2 = greenlet(test2)

gr1.switch()

四、Gevent模块

本质就是封装了greenlet模块，它能检测I/O并且遇到I/O自动切换到另外一个任务执行；可以帮我们提升效率

#_*_ coding:utf-8 _*_

# Author:Simon

# Datetime:2019/9/2 21:39

# Software:PyCharm

import gevent

import requests,time

start=time.time()

def f(url):

    print('GET: %s' % url)

    resp =requests.get(url)

    data = resp.text

    print('%d bytes received from %s.' % (len(data), url))

gevent.joinall([

        gevent.spawn(f, 'https://www.jd.org/'),

        gevent.spawn(f, 'https://www.xiaohua.com/'),

        gevent.spawn(f, 'https://www.baidu.com/'),

        gevent.spawn(f, 'https://www.taobao.com/'),

])

# f('https://www.jd.org/')

# f('https://www.xiaohua.com/')

# f('https://baidu.com/')

# f('https://www.taobao.com/')

#

# print("cost time:",time.time()-start)

gevent异步提交任务

from gevent import monkey;monkey.patch_all()

import gevent

import time

def eat(name):

    print('%s eat 1' % name)

    time.sleep(3)

    print('%s eat 2' % name)

def play(name):

    print('%s play 1' % name)

    time.sleep(4)

    print('%s play 2' % name)

g1=gevent.spawn(eat,'simon')

g2=gevent.spawn(play,'zhuzhu')

# time.sleep(5)

# g1.join()

# g2.join()

gevent.joinall([g1,g2]) #相当于上边两行代码

打印：

simon eat 1

zhuzhu play 1

simon eat 2

zhuzhu play 2

基于gevent模块实现并发的套接字通信

单线程、多任务的I/O操作。

#基于gevent实现

from gevent import monkey,spawn;monkey.patch_all()

from socket import *

def communicate(conn):

    while True:

        try:

            data=conn.recv(1024)

            if not data:break

            conn.send(data.upper())

        except ConnectionResetError:

            break

    conn.close()

def server(ip,port):

    server = socket(AF_INET, SOCK_STREAM)

    server.bind((ip,port))

    server.listen(5)

    while True:

        conn, addr = server.accept()

        spawn(communicate,conn) #造一个协程对象，提交完这个对象它不会执行

    server.close()

if __name__ == '__main__':

    g=spawn(server,'127.0.0.1',8090)

    g.join()
##客户端

from socket import *

from threading import Thread,currentThread

def client():

    client=socket(AF_INET,SOCK_STREAM)

    client.connect(('127.0.0.1',8090))

    while True:

        client.send(('%s hello' %currentThread().getName()).encode('utf-8'))

        data=client.recv(1024)

        print(data.decode('utf-8'))

    client.close()

if __name__ == '__main__':

    for i in range(500):

        t=Thread(target=client)

        t.start()

相关文章