在 python 中测量长时间间隔

Question

在 Python 3.x 中搜索了不同的时间测量方法后，我决定使用 perf_counter()来自 time 模块的函数。当我用一个需要几秒钟到运行的函数对其进行测试时，它工作正常，但我想从中提取计时结果的代码需要数十小时到运行.

今天我得到了结果，令我惊讶的是计时结果是几分之一秒的数量级，这是荒谬的。因此，我来请教大家为什么会出现这种情况，以及如何在Python 3.x.

中准确测量长的时间间隔

使用代码如下：

optimization_times = []
for i in range(30):
    # Search parameters on train set
    print("Round %d" % i)
    time_start = time.perf_counter()
    solution = metaheuristic.optimize()
    time_end = time.perf_counter()
    # Keep time spent
    optimization_times.append(time_end - time_start)

操作系统：Ubuntu18.04

提前致谢。

Answer 1

time.perf_counter() → float

Return the value (in fractional seconds) of a performance counter, i.e. a clock with the highest available resolution to measure a short duration. It does include time elapsed during sleep and is system-wide. The reference point of the returned value is undefined, so that only the difference between the results of consecutive calls is valid.

--

"what is a fractional second?"

Fractional second is the part of the time that is not an integer. So if you have a time like 12345678.9 the fractional second is 0.9

(Basile Starynkevitch)

可能的解决方案是timeit：

import timeit
import time

def func():
    time.sleep(0.05)

timeit.timeit(lambda: func(), number=10)

输出：

0.528169795999986

Answer 2

你看到了环绕。

来自docs：

... a clock with the highest available resolution to measure a short duration.

如果你的间隔是几十个小时，你应该坚持time.time()，它有足够的分辨率满足您的需求。

如果你认为你真的需要一个疯狂的数字精度，然后结合 time.time() 和 perf_counter()，旁边还有一个程序定期记录这两个值，以便您可以将 perf_counter 偏移同步到全球时间。这样的日志对应使您的 48 位计数器更宽一些，它可以让您观察每个环绕事件。

在 python 中测量长时间间隔

Measuring long time intervals in python

python

python-3.x

intervals

timing

`time.perf_counter()` → float

"what is a fractional second?"

在 python 中测量长时间间隔

Measuring long time intervals in python

python

python-3.x

intervals

timing

time.perf_counter() → float

"what is a fractional second?"

`time.perf_counter()` → float