Python обработчик сигналов не работает через некоторое время

Question

У меня есть обработчик сигналов, который выглядит хорошо работающим в любой части кода, кроме этого цикла:

    while not interrupted and time_to_sleep > 0:
        logging.info(f"Zzzz... interrupted={interrupted}, time_to_sleep={time_to_sleep}")
        time_to_sleep_now = min(interval_to_check_signals, time_to_sleep)
        time.sleep(time_to_sleep_now)
        time_to_sleep = max(0, time_to_sleep - time_to_sleep_now)

Когда выполняется эта часть кода, я могу нажать CTRL + C или CTRL + Z, которые не работают. пример:

INFO:root:Zzzz... interrupted=False, time_to_sleep=55
INFO:root:Zzzz... interrupted=False, time_to_sleep=50
INFO:root:Zzzz... interrupted=False, time_to_sleep=45
^C^C^CINFO:root:Zzzz... interrupted=False, time_to_sleep=40
^CINFO:root:Zzzz... interrupted=False, time_to_sleep=35
^C^C^C^C^C^C^CINFO:root:Zzzz... interrupted=False, time_to_sleep=30
^ZINFO:root:Zzzz... interrupted=False, time_to_sleep=25
^Z^Z^Z^ZINFO:root:Zzzz... interrupted=False, time_to_sleep=20
INFO:root:Zzzz... interrupted=False, time_to_sleep=15
INFO:root:Zzzz... interrupted=False, time_to_sleep=10

Моя полная программа такая:

"""
xxx
"""
import logging
import os
import signal
import time

# Load Environment Variables
TIME_TO_SLEEP_BETWEEN_CHECK_QUEUE = int(os.getenv('TIME_TO_SLEEP_BETWEEN_CHECK_QUEUE', 5 * 60))  # time in seconds

logging.basicConfig(level=logging.INFO)  # Use only for debug locally

interrupted = False


def signal_handler(signal: int, frame):
    """It's an Handler for when a system signal is made. (System Signal is like a CTRL+C command, or other exit order)

    It'll flag a global variable that is to graceful exit.
    For example, when kubernetes does not need some pod, it will send a signal to pod to close,
    but because this service have a long sleep time, it's important to wake up sometimes only to check signals,
    and die graceful.
    :param signal: Signal code
    :param frame:
    :return:
    """
    global interrupted
    interrupted = True
    logging.warning(f"Signal '{signal}' received, the program will stop")


def sleep_and_look_for_signals(time_to_sleep: int, interval_to_check_signals: int = 5) -> None:
    """Sleep some time, but while is sleeping, sometimes wakes up to check if is interrupted

    :param time_to_sleep:
    :param interval_to_check_signals:
    :return:
    """
    global interrupted
    logging.info("Sleeping...")
    while not interrupted and time_to_sleep > 0:
        logging.info(f"Zzzz... interrupted={interrupted}, time_to_sleep={time_to_sleep}")
        time_to_sleep_now = min(interval_to_check_signals, time_to_sleep)
        time.sleep(time_to_sleep_now)
        time_to_sleep = max(0, time_to_sleep - time_to_sleep_now)
    logging.info("Wake up!")


def more_messages_in_queue_bla_bla_bla():
    # This is an example
    return False


if __name__ == "__main__":
    # Set handler to signal
    signal.signal(signal.SIGHUP, signal_handler)  # CODE 1
    signal.signal(signal.SIGINT, signal_handler)   # CODE 2
    signal.signal(signal.SIGTERM, signal_handler)  # CODE 15

    while True:
        # Signal to exit handled was triggered?
        if interrupted:
            logging.warning("Graceful exit")
            break

        time_to_sleep_until_next_check = TIME_TO_SLEEP_BETWEEN_CHECK_QUEUE  # Reset to default sleep time
        # Do a lot of work here...
        # Do a lot of work here...
        # Do a lot of work here...
        # Do a lot of work here...
        if more_messages_in_queue_bla_bla_bla():
            time_to_sleep_until_next_check = 0

        # sleep
        logging.info(f"Sleep {time_to_sleep_until_next_check} seconds...\n")
        sleep_and_look_for_signals(time_to_sleep_until_next_check)