deep sleep and catching BaseException cause crash into hard fault handler

[vladak]

CircuitPython version

Adafruit CircuitPython 8.0.0-beta.6 on 2022-12-21; Adafruit QT Py ESP32S2 with ESP32S2

Code/REPL

import time
import traceback

import alarm
import supervisor


def main():
    print("Sleeping for 10 seconds")
    time.sleep(10)

    sleep_period = 15
    time_alarm = alarm.time.TimeAlarm(monotonic_time=time.monotonic() + sleep_period)
    print(f"Entering deep sleep for {sleep_period} seconds")
    alarm.exit_and_deep_sleep_until_alarms(time_alarm)


try:
    main()
except BaseException as e:  # pylint: disable=broad-except
    # This assumes that such exceptions are quite rare.
    # Otherwise, this would drain the battery quickly by restarting
    # over and over in a quick succession.
    print("Code stopped by unhandled exception:")
    print(traceback.format_exception(None, e, e.__traceback__))
    RELOAD_TIME = 10
    print(f"Performing a supervisor reload in {RELOAD_TIME} seconds")
    time.sleep(RELOAD_TIME)
    supervisor.reload()

Behavior

The code crashes into hard fault handler. The QtPy has to be restarted by the reset button.

Description

The QtPy is connected to stable USB power source (my laptop) so in reality the deep sleep will not happen.

This is reproducible 100% of time.

My hypothesis is that the DeepSleepRequest gets raised by the alarm and given it is based on BaseException, the catch block will try to handle it and somehow this is toxic to the traceback line.

Additional information

If I replace the BaseException with just Exception, the code does not crash anymore and properly says Pretending to deep sleep until alarm, CTRL-C or file write..

More details on vladak/shield#14.

[jepler]

Yes, the implementation of deep_sleep_... is to raise a DeepSleepRequest exception. It may be that printing this exception causes a problem, or something else is weird.

You should probably either change this to catch Exception or (Exception, KeyboardInterrupt), rather than BaseException, since even if it "worked" it would erroneously turn a DeepSleepRequest into a 10s delay & supervisor reload.

[jepler]

Confirmed it's specifically something to do with printing a DeepSleep exception.

some random old FW on a board I grabbed:

Adafruit CircuitPython 9.1.0-beta.3-50-g9b85fe5766-dirty on 2024-07-09; Adafruit MagTag with ESP32S2
>>> import alarm
>>> try:
...     alarm.exit_and_deep_sleep_until_alarms()
... except BaseException as e:
...     ee = e
...     
...     
... 
>>> id(ee)
1065359200
>>> type(ee)
<class 'DeepSleepRequest'>
>>> print(ee)

[08:31:34.335] Disconnected