Python 之并发编程之协程

一．协程

'''

def gen():

    for i in range(10):

        yield i

# 初始化生成七函数 返回生成器对象,简称生成器

mygen = gen()

for i in mygen:

    print(i)

'''

# (1) 用协程改写成生产者消费者

'''

def producer():

    for i in range(100):

        yield i

def consumer():

    g = producer()

    for i in g:

        print(i)

'''

# (2) 协程的具体实现

from greenlet import greenlet

import time

'''

switch 利用它进行任务的切块,一般在阻塞的时候切块

只能默认手动切换

缺陷: 不能规避io,不能自动实现遇到阻塞就切换

'''

"""

def eat():

    print("eat one")

    # 手动切换play这个协程中

    g2.switch()

    time.sleep(1)

    print("eat two")

def play():

    print("play one")

    time.sleep(1)

    print("play two")

    g1.switch()

g1 = greenlet(eat)

g2 = greenlet(play)

g1.switch()

'''

eat one

play one

play two

eat two

'''

"""

# (3) 缺陷:gevent不能够识别time.sleep 是阻塞

"""

import gevent

# gevent 其中有一个spawn 类似于switch ,也是切换任务的

import time

def eat():

    print("eat one")

    time.sleep(1)

    print("eat two")

def play():

    print("play one")

    time.sleep(1)

    print("play two")

# 利用gevent 创建协程对象g1

g1 = gevent.spawn(eat)

#利用gevent创建协程对象g2

g2 = gevent.spawn(play)

# 协程的阻塞是join 等待当前协程执行完毕之后,再向下执行

g1.join()  #阻塞直到g1协程执行完毕

g2.join()  #阻塞直到g2协程执行完毕

print("主线程执行完毕")

"""

# (4) 进阶 用gevent.sleep 来取代time.sleep()

'''

import gevent

def eat():

    print("eat one")

    gevent.sleep(1)

    print("eat two")

def play():

    print("play one")

    gevent.sleep(1)

    print("play two")

g1 = gevent.spawn(eat)

g2 = gevent.spawn(play)

g1.join()

g2.join()

print("主线程执行完毕")

'''

# (5) 终极解决识别问题

# spawn gevent 中spawn 遇到阻塞会自动切换协程任务

from gevent import monkey

# 把patch_all 下面引入的所有模块中的阻塞识别出来

monkey.patch_all()

import time

import gevent

def eat():

    print("eat one")

    time.sleep(1)

    print("eat two")

def play():

    print("play one")

    time.sleep(1)

    print("play two")

g1 = gevent.spawn(eat)

g2 = gevent.spawn(play)

g1.join()

g2.join()

print("主进程执行结束...")

二．协程例子