How to process SIGTERM signal gracefully?

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Let’s assume we have such a trivial daemon written in python:

def mainloop():
    while True:
        # 1. do
        # 2. some
        # 3. important
        # 4. job
        # 5. sleep

mainloop()

and we daemonize it using start-stop-daemon which by default sends SIGTERM (TERM) signal on --stop.

Let’s suppose the current step performed is #2. And at this very moment we’re sending TERM signal.

What happens is that the execution terminates immediately.

I’ve found that I can handle the signal event using signal.signal(signal.SIGTERM, handler) but the thing is that it still interrupts the current execution and passes the control to handler.

So, my question is – is it possible to not interrupt the current execution but handle the TERM signal in a separated thread (?) so that I was able to set shutdown_flag = True so that mainloop() had a chance to stop gracefully?

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