Question

I’m having trouble figuring out how to do this.

I’m trying to run a python script for a set duration. And every 1/10 of the duration I need it to run something. The problem is this step can take any amount of time to complete. I cannot go over the maximum duration set at the start.

Example:
Duration 20 hours

Interval = 20/10 = 2 hours (This can change if it needs to)

Every two hours it runs function(). function() takes between 0-60 minutes to complete. And then it sleeps. How can I make it so that it continues to run 9 more times, but doesn’t go over the max duration?

Answer 1

Perhaps you can use signals. The idea is you set a signal handler to get called when a SIGALRM is generated. In the signal handler you can call function. Then you reset the alarm and do it again. This is a basic example just to give you an idea.

import signal
...
signal.signal(signal.SIGALRM, alarm_handler)  # set the signal handler
signal.alarm(interval)                        # set the alarm
...
def alarm_handler(signum, stack):
    # call function
    function()

Once the alarm goes off, you call function() and then reset the alarm:

signal.signal(signal.SIGALRM, alarm_handler)
signal.alarm(interval)

Or you can use signal.setitimer to automatically configure interval alarms, however I am not sure how that will work with large timeslices (its used for microsleeps).

NOTE: You must call signal.alarm() from the main thread.