Example using spin_some might throw exception

[hdino]

The examples in this repository are besides the ROS2 tutorials the first place to learn ROS2. Therefore, many public repositories, for instance of universities or research institutes, contain code that uses exactly the same procedures as shown here.

The minimal_publisher example shows how to use rclcpp::spin_some. However, as pointed out in ros2/rclcpp#1066, rclcpp::spin_some will throw an exception if the program received a SIGINT and processed the shutdown after checking rclcpp::ok(), but before constructing the SingleThreadedExecutor in rclcpp::spin_some. This behaviour can easily be triggered by:

while (rclcpp::ok())
{
    std::this_thread::sleep_for(std::chrono::seconds(1));
    rclcpp::spin_some(ros_node);
}

@fujitatomoya created a working example.

In ros2/rclcpp#1066 we already discussed some possible solutions, but we thought it's better to discuss this issue here. What are your opinions?

[fujitatomoya]

suggest to put spin_some in a try-catch block in example code, i guess.

[fujitatomoya]

@hdino

are you gonna make a PR on this?

[hidmic]

@hdino friendly ping.

[fujitatomoya]

@hdino @hidmic

could you take a look at #270?

[luym11]

I also recently have the issue of ros2/rclcpp#1066, and the fix I found out is something similar to luym11@26dfef3.
Is this the correct way to do this? I thought that ROS should already have a signal handler such that I do not need to override it like this.
Thanks!