14 并发编程-(协程)-greenlet模块&gevent模块

1、实现多个任务之间进行切换，yield、greenlet都没有实现检测I/O，greenlet在实现多任务切换下更简单

from greenlet import greenlet

def eat(name):

    print(f"{name} eat 1")

    g2.switch('egon') # 切换

    print(f"{name} eat 2")

    g2.switch()

def play(name):

    print(f"{name} play 1")

    g1.switch()

    print(f"{name} play 2")

g1 = greenlet(eat)

g2 = greenlet(play)

g1.switch('egon') # 程序从此处执行

egon eat 1

egon play 1

egon eat 2

egon play 2

2、一个协程遇到IO操作自动切换到其它协程（如何实现检测IO，yield、greenlet都无法实现，就用到了gevent模块（select机制））

2.1 gevent模块

可以轻松的实现并发或异步编程，在gevent中用到的主要模式是Greenlet,

2.1.1、遇到io阻塞时会自动切换任务 --只实现识别gevent可以识别的阻塞

# 遇到io阻塞会自动切换任务

import gevent,time

def eat(name):

    print(f"{name} eat1")

    gevent.sleep(2)  # 模拟io阻塞

    print(f"{name} eat2")

def play(name):

    print(f"{name} play1")

    gevent.sleep(2)

    print(f"{name} play2")

start = time.time()

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

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

g1.join()

g2.join()

stop = time.time()

print(stop-start)

alex eat1

alex play1

alex eat2

alex play2

2.007000207901001

2.1.2、实际情况中的应用gevent  打补丁(monkey.patch_all()) 识别 所有阻塞

alex eat1
alex play1
alex eat2
alex play2
2.005999803543091

3、基于gvent模块实现并发的套接字通信

服务端：

# 基于 gevent

from gevent import monkey;monkey.patch_all()

import socket

import gevent

def Server(ip_port):

    server = socket.socket(socket.AF_INET,socket.SOCK_STREAM)

    server.bind(ip_port)

    server.listen(5)

    while True:

        conn,addr = server.accept()

        gevent.spawn(communicate,conn)

    server.close()

def communicate(conn):

    while True:

        try:

            data = conn.recv(1024).decode('utf-8')

            conn.send(data.upper().encode('utf-8'))

        except Exception as e:

            print(e)

            break

    conn.close()

if __name__ == '__main__':

    ip_port = ('127.0.0.1',8080)

    Server(ip_port)

    # g = gevent.spawn(Server,ip_port)

    # g.join()

客户端：启动500个线程模拟500个客户端向服务端发消息

import socket

from threading import Thread,currentThread

def client():

    client = socket.socket(socket.AF_INET,socket.SOCK_STREAM)

    ip_port = ('127.0.0.1',8080)

    client.connect(ip_port)

    while True:

        client.send(f"{currentThread().getName()} hello".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()