import gevent

import gevent,time       ##gevent  是 第三方库  
from gevent import monkey
from urllib import request
monkey.patch_all()    ##  让程序变成IO

def  libs(url):
    print('Get %s '%url)
    requ = request.urlopen(url)
    re_requ = requ.read()

urls = ['https://www.python.org/',
        'https://www.yahoo.com/',
        'https://github.com/' ]
time_star = time.time()
for i in urls:
    libs(i)
print('损耗的时间是 %s'%(time.time()-time_star))

ootime =  time.time()
gevent.joinall([
    gevent.spawn(libs,'https://www.python.org/'),
    gevent.spawn(libs,'https://www.yahoo.com/'),
    gevent.spawn(libs,'https://github.com/'),

])
print('异步所需的时间是 %s'%(time.time()-ootime))

结果

F:python_oldboyScriptspScriptspython.exe F:/python_oldboy/geve/爬虫练习.py
Get https://www.python.org/
Get https://www.yahoo.com/
Get https://github.com/
损耗的时间是 10.494600296020508
Get https://www.python.org/
Get https://www.yahoo.com/
Get https://github.com/
异步所需的时间是 3.925224542617798

---

import gevent
##安装第三方库  gevent, 可实现 同步或者异步编程
def foo():
    print('Running in foo')  #1
    gevent.sleep(2)
    print('context switch to foo again') #4

def bar():
    print('running in bar')  #2
    gevent.sleep(1)
    print('context switch back bar') #3

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