python协程的使用

协程

微线程
遇到IO就切换

import gevent

def foo():

    print('hello bar')

    gevent.sleep(2)

    print('hello bar too')

def bar():

    print('hello foo')

    gevent.sleep(1)

    print('hello foo too')

gevent.joinall([gevent.spawn(foo),gevent.spawn(bar)])

协程gevent并发爬取网页

__author__ = 'Mr.Bool'

import gevent

import time

from urllib import request

from gevent import monkey

monkey.patch_all()

def f(url):

    print("GET:",url)

    resp=request.urlopen(url)

    data=resp.read()

    print("%d bytes is received from %s "%(len(data),url))

urls=[

    "https://www.python.org",

    'https://github.com/',

    'https://www.hao123.com'

]

tims_start=time.time()

for url in urls:

    f(url)

print("同步cost",time.time()-tims_start)

async_time_start=time.time()

gevent.joinall(

    [

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

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

        gevent.spawn(f,'https://www.hao123.com'),

     ]

)

print("异步cost",time.time()-async_time_start) 
 

通过gevent实现单线程下的多socket并发

import sys

import socket

import time

import gevent

from gevent import socket,monkey

monkey.patch_all()

def server(port):

    s = socket.socket()

    s.bind(('0.0.0.0', port))

    s.listen(500)

    while True:

        cli, addr = s.accept()

        gevent.spawn(handle_request, cli)

def handle_request(conn):

    try:

        while True:

            data = conn.recv(1024)

            print("recv:", data)

            conn.send(data)

            if not data:

                conn.shutdown(socket.SHUT_WR)

    except Exception as  ex:

        print(ex)

    finally:

        conn.close()

if __name__ == '__main__':

    server(8001)

import socket

client:

HOST = 'localhost'    # The remote host

PORT = 8001           # The same port as used by the server

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

s.connect((HOST, PORT))

while True:

    msg = bytes(input(">>:"),encoding="utf8")

    s.sendall(msg)

    data = s.recv(1024)

    #print(data)

    print('Received', repr(data))

s.close()  

100个:

import socket

import threading

def sock_conn():

    client = socket.socket()

    client.connect(("localhost",8001))

    count = 0

    while True:

        #msg = input(">>:").strip()

        #if len(msg) == 0:continue

        client.send( ("hello %s" %count).encode("utf-8"))

        data = client.recv(1024)

        print("[%s]recv from server:" % threading.get_ident(),data.decode()) #结果

        count +=1

    client.close()

for i in range(100):

    t = threading.Thread(target=sock_conn)

    t.start()

事件驱动：
根据事件做出反应，先将事件装进队列，然后再一个一个取出。

__author__ = 'Mr.Bool'

import gevent

def foo():

    print('hello bar')

    gevent.sleep(2)

    print('hello bar too')

def bar():

    print('hello foo')

    gevent.sleep(1)

    print('hello foo too')

gevent.joinall([gevent.spawn(foo),gevent.spawn(bar)])
  

网页

__author__ = 'Mr.Bool'

import gevent

import time

from urllib import request

from gevent import monkey

monkey.patch_all()

def f(url):

    print("GET:",url)

    resp=request.urlopen(url)

    data=resp.read()

    print("%d bytes is received from %s "%(len(data),url))

urls=[

    "https://www.python.org",

    'https://github.com/',

    'https://www.hao123.com'

]

tims_start=time.time()

for url in urls:

    f(url)

print("同步cost",time.time()-tims_start)

async_time_start=time.time()

gevent.joinall(

    [

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

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

        gevent.spawn(f,'https://www.hao123.com'),

     ]

)

print("异步cost",time.time()-async_time_start)  

select

__author__ = 'Mr.Bool'

import select

import socket

import queue

server=socket.socket()

server.bind(('localhsot',9999))

server.listen(1000)

server.setblocking(False)

intputs=[server,]

outputs=[]

msg_dic={}

while True:

    readable,writeable,excepational=select.select(intputs,outputs,intputs)

    for r in readable:

        if r is server:

            print("有新的链接")

            conn,addr=server.accept()

            intputs.append(conn)

            msg_dic[conn]=queue.Queue()

        else:

            data=r.recv(1024)

            print(data)

            msg_dic[r].put(data)

            outputs.append(r)

    for w in writeable:

        data_to_client=msg_dic[w].get()

        w.send(data_to_client)

        outputs.remove(w)

    for e in excepational:

        if e in outputs:

            outputs.remove(e)

        intputs.remove(e)

        del msg_dic[e]