Is there a way to execute a python script with consistent execution time by time padding if necessary?

Question

I know the execution time for any python program shall depend on the OS and cannot be controlled by the User. But what I want is the program to go in sleep if the execution time is lower than necessary.

Let's say I have a python program which has a print statement at the end.

def foo():
    ...
    ...
    return(ans)

print(foo())

Using timeit I have evaluated the range of execution time taken for foo. Let it be from 0.8 seconds to 5.5 seconds. I choose the execution time of the complete script as 10 seconds to be on the safe side.

I want the program to add delay of 9.2 seconds before print statement if the execution of foo was completed in 0.8 seconds. Likewise a delay of 4.5 seconds if execution was completed in 5.5 seconds.

How precise do you need to be?

ddejohn
– ddejohn

2022-03-19 04:59:14 +00:00
Commented Mar 19, 2022 at 4:59 — ddejohn
– ddejohn, Commented Mar 19, 2022 at 4:59
@ddejohn not much, a resolution of 0.1 seconds works.

pani3610
– pani3610

2022-03-19 05:04:00 +00:00
Commented Mar 19, 2022 at 5:04 — pani3610
– pani3610, Commented Mar 19, 2022 at 5:04

Keith · Accepted Answer · 2022-03-19 05:27:48Z

1

You basically just have to sleep for the amount of time that is the difference between the maximum time and actual execution time. you could also make a general purpose decorator.

class padtime:
    def __init__(self, maxtime):
        self.maxtime = float(maxtime)

    def __call__(self, f):
        def _f(*args, **kwargs):
            start = time.time()
            ret = f(*args, **kwargs)
            end = time.time()
            delay = self.maxtime - (end - start)
            if delay > 0.0:
                time.sleep(delay)
            return ret
        return _f

@padtime(9.5)
def foo():
    ...
    return("Answer")

that could be applied to any function.

answered Mar 19, 2022 at 5:27

Keith

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BrokenBenchmark · Accepted Answer · 2022-03-19 05:08:36Z

0

You can measure the execution time of foo() using two calls to time.time(). You can then compute the amount of time to stall the execution of the program using the computed execution time of foo():

import time

def foo():
    ...

start_time = time.time()
foo()
end_time = time.time()
if end_time - start_time < 10:
    time.sleep(10 - (end_time - start_time))

Note that we use time.sleep() rather than a while loop that repeatedly checks whether enough time has elapsed, since busy waiting wastes resources.

answered Mar 19, 2022 at 5:08

BrokenBenchmark

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4 Comments

ddejohn Over a year ago

Kinda silly to bring up "wasting resources" when time is a resource and OP wants to intentionally waste it but ¯\_(ツ)_/¯

pani3610 Over a year ago

works well within the resolution required. Thanks! @BrokenBenchmark

BrokenBenchmark Over a year ago

@ddejohn Yeah, but busy waiting is a general pattern one should avoid. I was going to comment that on your answer, but it was deleted before I could answer. (I wasn't the one who downvoted, for the record.)

Keith Over a year ago

@ddejohn However, time is a different resource from CPU cycles. A sleep allows another process to use those cycles.

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