demo.py

import threading


class Task(object):
    def __init__(self):
        self.lock = threading.RLock()
        self.cv = threading.Condition(self.lock)
        self.running = True

    def task1(self):
        with self.lock:
            running = self.running

        while running:
            print("starting task1")
            with self.lock:
                self.cv.wait(3)
                running = self.running
            print("task1 completed!")

    def task2(self):
        with self.lock:
            running = self.running

        while running:
            print("starting task2")
            with self.lock:
                self.cv.wait(3)
                running = self.running
            print("task2 completed!")

    def stop(self):
        with self.lock:
            self.running = False
            self.cv.notify_all()
        
    def start(self):
        self.thread1 = threading.Thread(target=self.task1)
        self.thread2 = threading.Thread(target=self.task2)
        self.thread1.start()
        self.thread2.start()

    def join(self):
        self.thread1.join()
        self.thread2.join()


if __name__ == "__main__":
    task = Task()
    task.start()

    try:
        task.join()
    except KeyboardInterrupt:
        print("KeyboardInterrupt has been caught.")
    finally:
        task.stop()
        task.join()