寫在前面

• 上一篇文章[Python3簡單實(shí)現(xiàn)多任務(wù)(多進(jìn)程篇)]已經(jīng)介紹了python多進(jìn)程實(shí)現(xiàn)多任務(wù)的簡單實(shí)現(xiàn)方法;
• 這次講一講python創(chuàng)建多任務(wù)另外兩種常見的方式:

• 協(xié)程和線程

線程多任務(wù)實(shí)現(xiàn)1:直接使用Thread創(chuàng)建線程

from threading import Thread
import threading
import os
import time
import random

def not_know(thread_num):
    
    print("第%d線程吟唱:不知天上宮闕"%(thread_num))
    time.sleep(random.random())
    print("第%d線程吟唱:今夕是何年"%(thread_num))
    time.sleep(random.random())
    print("第%d號線程:<吟唱古詩>任務(wù)結(jié)束..."%(thread_num))

def main():
    for i in range(1, 6):
        num = len(threading.enumerate())
        print("當(dāng)前線程數(shù)為:%d"%num)
        t = Thread(target=not_know, args=(i,))
        t.start()
        time.sleep(0.8)

if __name__ == "__main__":
    print("--->主函數(shù)開始運(yùn)行<---")
    main()
    print("--->主函數(shù)運(yùn)行完畢<---")

線程多任務(wù)實(shí)現(xiàn)2:定義類繼承threading.Thread,然后重寫run方法(run方法相當(dāng)于功能函數(shù))

from threading import Thread
import threading
import os
import random
import time

class the_cosmetic(threading.Thread):
    def __init__(self, num):
        self.num = num
        # 一定要記得調(diào)用父類構(gòu)造方法
        threading.Thread.__init__(self)

    def run(self):
        print("-->第%d線程開始執(zhí)行<--"%self.num)
        time.sleep(random.random())
        print("%d最有效的化妝品是什么?"%self.num)
        time.sleep(random.random())
        print("%dPhotoshop是最好的化妝品!"%self.num)
        time.sleep(random.random())
        print("-->第%d線程執(zhí)行完畢<--"%self.num)

def main():
    print("-------->開始創(chuàng)建線程<--------")

    for i in range(1, 6):
        t = the_cosmetic(i)
        t.start()

    print("-------->線程創(chuàng)建完畢<--------")

if __name__ == "__main__":
    main()

協(xié)程多任務(wù)實(shí)現(xiàn)1:gevent(使用簡單,推薦!需要pip安裝gevent)

sudo pip3 install gevent

import time
import random
import gevent
from gevent import monkey

monkey.patch_all()

def peach(name):
    for i in range(1, 6):
        start_time = time.time()
        time.sleep(random.random())
        end_time = time.time()
        # 使用 round() 控制小數(shù)點(diǎn)位數(shù)!
        print("%s產(chǎn)出第%s個(gè)桃子,耗時(shí)%s"%(name, i, round(end_time - start_time, 2)))

def apple(name):
    for i in range(1, 8):
        start_time = time.time()
        time.sleep(random.random())
        end_time = time.time()
        print("%s產(chǎn)出第%s個(gè)蘋果,耗時(shí)%s"%(name, i, round(end_time - start_time, 2)))

def main():
    # 注意:下面的語句,沒有等號! 沒有等號! 沒有等號!
    gevent.joinall([
        gevent.spawn(peach,"LI"),
        gevent.spawn(apple,"HO"),
        ])

if __name__ == "__main__":
    main()

協(xié)程多任務(wù)實(shí)現(xiàn)2:yield實(shí)現(xiàn)協(xié)程(yield最底層,最靈活,是python自帶的模塊)

import time

def to_activate():
    yield
    print("吃早飯")
    print("讀文檔")
    yield
    print("吃中午飯")
    print("寫程序")
    yield
    print("吃晚飯")
    print("解bug")

def to_sleep():
    yield
    print("午睡")
    yield
    print("晚休")

def main():
    print("程序員的一天")
    activate = to_activate()
    sleep = to_sleep()

    # 利用yield開始在兩個(gè)函數(shù)間跳轉(zhuǎn)
    next(activate)
    next(sleep)
    next(activate)
    next(sleep)
    next(activate)

    print("程序員的一天結(jié)束了")



if __name__ == "__main__":
    main()

協(xié)程多任務(wù)實(shí)現(xiàn)3:greenlet實(shí)現(xiàn)協(xié)程(模塊須通過pip單獨(dú)安裝,個(gè)人感覺這個(gè)模塊封裝的并不夠好,所以放到最后,僅供了解)

sudo pip3 install greenlet

import time
from greenlet import greenlet

activate = None
sleep = None

def to_activate():
    print("吃早飯")
    print("讀文檔")
    sleep.switch()
    print("吃中午飯")
    print("寫程序")
    print("吃晚飯")
    print("解bug")

def to_sleep():
    print("午睡")
    activate.switch()
    print("晚休")

def main():
    global activate
    global sleep
    print("程序員的一天")
    activate = greenlet(to_activate)
    sleep = greenlet(to_sleep)

    #從activate開始執(zhí)行
    activate.switch()
    print("程序員的一天結(jié)束了")



if __name__ == "__main__":
    main()

小結(jié)

• 線程與進(jìn)程相比,占用資源更少,但線程依賴于進(jìn)程,一個(gè)進(jìn)程可以有多個(gè)線程,進(jìn)程完成任務(wù)依賴于內(nèi)部的線程;
• 協(xié)程解決了線程之間爭用資源引發(fā)的資源浪費(fèi),所以協(xié)程比線程占用的資源更少.