只有含有i/o时多线程才会比单线程快

import threading

import time

ind=3

def single():

    for j in range(ind):

        for i in range(5000):

            w=2*i

            #print(w)

def s():

    for i in range(5000):

        w=2*i

        #print(w)

def multi():

    threa=[]

    for j in range(ind):

        t=threading.Thread(target=s)

        threa.append(t)

    for t in threa:

        t.start()

    for t in threa:

        t.join()

if __name__ == '__main__':

    dan_sum=0

    multi_sum=0

    start=time.time()

    single()

    end=time.time()

    sum=0

    sum1=0

    sum=end-start

    start=time.time()

    multi()

    end=time.time()

    sum1=end-start

    print('single',sum,'multi',sum1,dan_sum,multi_sum)