python node with Recorder does not exit with CTRL-C

[tonynajjar]

Description

A rclpy node instantiating a rosbag2_py.Recorder does not exit with CTRL-C

Expected Behavior

It should exit cleanly

Actual Behavior

It just hangs

To Reproduce

import rclpy

from rclpy.node import Node
from rosbag2_py import Recorder

class RosBagRecorder(Node):
    def __init__(self):
        super().__init__("rosbag_recorder")
        self.recorder = Recorder()

def main():
    rclpy.init()
    node = RosBagRecorder()
    rclpy.spin(node)


if __name__ == "__main__":
    main()

System (please complete the following information)

• OS: Ubuntu 22
• ROS 2 Distro: Iron
• Install Method: source
• Version: iron latest

Additional context

** Add any other context about the problem here **

[MichaelOrlov]

@tonynajjar The code behave as expected by design.
It doesn't make sense to create rosbag2 recorder and spin node directly.
We have SingleThreadedExecuter inside Recorder::record(..) method which will spin the node and gracefully handle SIGINT and SIGTERM signals.

in your example, you are missing call for the

recorder.record(storage_options, record_options, "node_name")

Please refer to the

rosbag2/ros2bag/ros2bag/verb/record.py

Lines 255 to 260 in dcd239c

	recorder = Recorder()
	try:
	recorder.record(storage_options, record_options, args.node_name)
	except KeyboardInterrupt:
	pass

as an example of how to properly use it.

[tonynajjar]

The instantiation of a Recorder in any python script will block CTRL-C

from rosbag2_py import Recorder
import time

recorder = Recorder()
time.sleep(10)

Try to exit this script with CTRL-C before the sleep ends -> doesn't exit. Maybe CTRL-C will work if recorder.record is called but that shouldn't be a requirement

[MichaelOrlov]

@tonynajjar Yes it is true. We override signal handlers in the recorder constructor to handle them further on in blocking recorder::record(..) method.
Perhaps we can change this behavior and install signal handlers at the beginning of the recorder::record(..) method.

Out of curiosity what would be a use case for instantiating Recorder() instance and not using recorder::record(..) method after that?

[tonynajjar]

The use case is I want to have a node with a service server that when called, will start recording a bag with the help of the Recorder. A bit like what is asked in #685

So the Recorder exists but we only start recording when the service is called

[fujitatomoya]

The use case is I want to have a node with a service server that when called, will start recording a bag with the help of the Recorder.

@tonynajjar https://github.com/ros2/rosbag2?tab=readme-ov-file#controlling-recordings-via-services does not work for your use case?