5.1.25 协程

协程：单线程下的并发。又称微线程。是用户态的轻量级线程，即协程是由用户程序自己控制调度的

要遇到IO才切。

比线程开销更小。

修改共享数据不用加锁

yield greenlet都无法做到遇到IO就切换

gevent 可以监控多个任务之间的IO,遇到IO切换到另一个任务。

 

yield:

#并发执行
import time

def producer():
    g=consumer()
    next(g)
    for i in range(10000000):
        g.send(i)



def consumer():
    while True:
        res=yield


start_time=time.time()
producer()
stop_time=time.time()
print(stop_time-start_time)



#串行
import time

def producer():
    res=[]
    for i in range(10000000):
        res.append(i)
    return res


def consumer(res):
    pass


start_time=time.time()
res=producer()
consumer(res)
stop_time=time.time()
print(stop_time-start_time)

 

Greenlet:

#pip3 install greenlet
from greenlet import greenlet
import time

def eat(name):
    print('%s eat 1' %name)
    #time.sleep(10)   #遇到IO就不会自动切换了
    g2.switch('egon')
    print('%s eat 2' %name)
    g2.switch()

def play(name):
    print('%s play 1' %name )
    g1.switch()
    print('%s play 2' %name )


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

g1.switch('egon')

 

Gevent: 详见下一节