python 获取毫秒级时间问题

根据网上的一些说法，在python里获取ms级系统时间可以通过以下方式获取：

import datetime
print(datetime.datetime.now().microsecond)

但通过以下代码测试，发现返回的并不是ms的值，而是us的值：

import datetime

def getTime_ms():
    return (datetime.datetime.now().hour*3600 +\
            datetime.datetime.now().minute*60+\
            datetime.datetime.now().second )*1000+\
           datetime.datetime.now().microsecond/1000

def timetime():
    t = getTime_ms()
    while getTime_ms() - t < 500:
        pass
    a = getTime_ms()
    print(t, a, a- t)



if __name__ == '__main__':

    from timeit import timeit
    t = timeit('timetime()', 'from __main__ import timetime', number=1)
    print(t)

打印结果;

(35460614, 35461114, 500)
0.499531984329

 

上面实验不太直观，换一个直观点的：

def timetime():
    t1 = datetime.datetime.now()
    while 1:
        t2 = datetime.datetime.now()
        if (t2 - t1).microseconds >= 1:
            print(t2,t2.microsecond,t1,t1.microsecond,(t2-t1).seconds)
            break


if __name__ == '__main__':
    from timeit import timeit
    t = timeit('timetime()', 'from __main__ import timetime', number=1)
    print(t)
    #print (datetime.datetime.now())

输出

(datetime.datetime(2019, 4, 3, 10, 6, 20, 461882), 461882, datetime.datetime(2019, 4, 3, 10, 6, 20, 461863), 461863, 0)
7.10487365723e-05

 

def timetime():
    t1 = datetime.datetime.now()
    while 1:
        t2 = datetime.datetime.now()
        if (t2 - t1).microseconds >= 1000:
            print(t2,t2.microsecond,t1,t1.microsecond,(t2-t1).seconds)
            break


if __name__ == '__main__':
    from timeit import timeit
    t = timeit('timetime()', 'from __main__ import timetime', number=1)
    print(t)
    #print (datetime.datetime.now())

输出

(datetime.datetime(2019, 4, 3, 10, 13, 52, 76548), 76548, datetime.datetime(2019, 4, 3, 10, 13, 52, 75547), 75547, 0)
0.00104904174805