Python: How to make the function run unconditionally when the program ends?

Question

I must ensure that the end_event() function is executed at the end of the program. I tried to implement this as Python's atexit. However, when the .py file was converted to an exe file with a PyInstaller and closed with a click, it did not work. I would appreciate it if you could tell me a solution that always works. Have a good day.

import atexit
import signal
import pyupbit

def end_event():
    for keys in buy_list.keys():
        order = upbit.get_order(keys)
        if "state" in order:
            if(order['state'] == 'wait'):
                upbit.cancel_order(keys)
    exit(1)

atexit.register(end_event)
signal.signal(signal.SIGINT, end_event)

“closed with a click” — that’s effectively a KILL -9 in windows if it passes through the handling to the default OS behavior. — user2864740, Oct 03 '21 at 17:41
Then, is there no way to implement it on Python code in this case? (Crying..) — JustTemp, Oct 03 '21 at 17:47
Package it with a small PyTK wrapper (then you’ll have control over the UI aspect..)? — user2864740, Oct 03 '21 at 17:49
Launch a standalone (two-part) process? So when the “client” (ie. sub-process of the windows terminal) dies, the “server” can shutdown cleanly? — user2864740, Oct 03 '21 at 17:50
Interesting! I'll try this method, too. Thank you for your answer! — JustTemp, Oct 03 '21 at 17:51
There are probably existing libraries to help with “robust” Python apps. — user2864740, Oct 03 '21 at 17:52

score 0 · Accepted Answer · answered Oct 03 '21 at 17:55

There is no way to guarantee that code will run when the process exits, because there are ways to exit which do not permit any code to run.

User may pull the power cable. No code can run because there is no power.
External events (power outage, lightning strike), same as above.
Kill -9 or equivalent, e.g. Windows' TerminateProcess

Patterns for emergency cleanup.

The best pattern is: Never be in a state which requires emergency cleanup.

There is no guarantee that your cleanup will run because you could have a kill -9 or a power outage.
Therefore you need to be able to recover in that scenario.

See also: What does the POSIX standard say about thread stacks in atexit() handlers? What's the OS practice?

Python: How to make the function run unconditionally when the program ends?

1 Answers1

Patterns for emergency cleanup.