多并发之协程

协程

什么是协程？

协程就是单线程下实现并发。是由用户自己控制调度的，也就是说需要在应用程序里实现。

协程的实现

Greenlet模块

from greenlet import greenlet
import time

def eat(name):

																	print('%s eat 1'%name)
    g2.switch('rose')

																							print('%s eat 2'%name)
    g2.switch()
def play(name):

																													print('%s play1'%name)
    g1.switch()

																																	print('%s play2'%name)

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

g1.switch('lucy')

 

lucy eat 1

rose play1

lucy eat 2

rose play2

 

Greenlet可以很方便地实现切换，但是他不会监测IO，不能实现IO阻塞就切换。

Gevent模块

import gevent

def eat(name):

													print('%s eat 1' % name)
    gevent.sleep(2)

																			print('%s eat 2' % name)


def play(name):

																									print('%s play' % name)
    gevent.sleep(2)

																															print('%s play' % name)


g1 = gevent.spawn(eat, 'lucy')
g2 = gevent.spawn(play, 'lile')

g1.join()
g2.join()

 

lucy eat 1

lile play

lucy eat 2

lile play

 

Gevent模块提高了执行效率，实现了并发操作，但是gevent.sleep()就可以监测自身，如果把这个改成time.sleep()就不会切换任务了，但是gevent下有个宝贝：

from gevent import monkey;monkey.patch_all()
import gevent
import time
def eat(name):

																			print('%s eat 1' % name)
    time.sleep(2)

																									print('%s eat 2' % name)


def play(name):

																															print('%s play' % name)
    time.sleep(2)

																																					print('%s play' % name)


g1 = gevent.spawn(eat, 'lucy')
g2 = gevent.spawn(play, 'lile')

# g1.join()
# g2.join()    # 等待执行完才结束进程

gevent.joinall([g1,g2])  # 同上，等待所有

就把ＩＯ阻塞变成非阻塞，但是一定要在文件开头写上。