Python协程

计算密集型-->需要占用大量的CPU资源-->多进程
IO密集型-->需要网络功能，大量时间都在等待网络数据的到-->多线程、协程
进程、线程的调用由操作系统觉得，携程的调用由开发者自己决定

协程实现

import time

def A():
    while True:
        print("----A---")
        yield #函数里边包含yield 为生成器
        time.sleep(0.5)

def B(c):
    while True:
        print("----B---")
        c.next()
        time.sleep(0.5)

if __name__=='__main__':
    a = A()
    B(a)

greenlet

from greenlet import greenlet
import time


def test1():
    while True:
        print('------A-------')
        gr2.switch()
        time.sleep(0.5)


def test2():
    while True:
        print('------B-------')
        gr1.switch()
        time.sleep(0.5)


gr1 = greenlet(test1)
gr2 = greenlet(test2)

gr1.switch()

gevent

import gevent


def f(n):
    for i in range(n):
        print(gevent.getcurrent(), i)

        gevent.sleep(1)


g1 = gevent.spawn(f, 5)
g2 = gevent.spawn(f, 5)
g3 = gevent.spawn(f, 5)
g1.join()
g2.join()
g3.join()