Thread daemon seems to cause "terminate called without an active exception"

[PaulBouchier]

The idea of making a daemon thread so rate.sleep() doesn't get stuck seems good, but seems to have the side-effect of causing this output after rclpy.shutdown() is called:

terminate called without an active exception [ros2run]: Aborted

Reading the web indicates that it's caused by a running thread having to be aborted when the process shuts down. I propose a more conventional approach is needed - something like:

class my_class
__init__(self):
        # Run spin in a thread so Rate.sleep() works
        self.thread = threading.Thread(target=self.spin_thread)
        self.stop_thread_flag = False
        self.thread.start()

def spin_thread(self):
    # implement a thread that keeps calling spin_once() so rate.sleep() will work
    def spin_thread(self):
        while(self.stop_thread_flag == False and rclpy.ok()):
            rclpy.spin_once(self, timeout_sec=0.1)
            if (self.stop_thread_flag):
                return

main():
    # Destroy the node explicitly
    # (optional - otherwise it will be done automatically
    # when the garbage collector destroys the node object)
    my_class.stop_thread_flag = True
    time.sleep(0.2)
    move_parent.destroy_node()
    rclpy.shutdown()

The disadvantage is you need to wait for the thread to exit before shutting things down. But it seems better than exiting with an abort.

Thoughts?