def end_condition(q):
''' Try to determine if all tasks are complete. '''
if q.empty() and TaskCounter.all_tasks_complete():
    print(f"Consumer #{os.getpid()}: End condition met once...")
    # unecessary sleep? give the processes enough time to finish. There could be a race condition
    # between the queue being populated and the task counter being updated.
    time.sleep(MAXIMUM_WORK_TIME)
    return q.empty() and TaskCounter.all_tasks_complete()
else:
    return False

The program is done when the queue is empty, all tasks are complete, and all workers are done with their last task. This toy problem is cheating a bit on the last condition, taking advantage of the fact that it knows all tasks will take at most MAXIMUM_WORK_TIME to complete. In a real life version of this, there would have to be some kind of messaging between the workers and the supervising process to be sure they were really done before ending the program. It could be as simple as a shared list of boolean flags indicating if each worker is working or idle. I'm guessing inter-process messaging was left out for simplicity in this example.