Setting name parameter leads to duplicate nodes with same name

[g-argyropoulos]

Bug report

Required Info:

• Operating System:
  • Ubuntu 22.04
• Installation type:
  • Binaries
• DDS implementation:
  • rmw_cyclonedds_cpp

Steps to reproduce issue

ros2 launch moveit2_tutorials moveit_cpp_tutorial.launch.py

Expected behavior

A single /moveit_cpp_tutorial node and a single /rviz2 node will be created.

Actual behavior

Two /moveit_cpp_tutorial and /rviz2 nodes were created.

~$ ros2 node list
WARNING: Be aware that are nodes in the graph that share an exact name, this can have unintended side effects.
/controller_manager
/joint_state_broadcaster
/moveit_cpp_tutorial
/moveit_cpp_tutorial
/moveit_cpp_tutorial_private_94809022977232
/panda_arm_controller
/panda_hand_controller
/robot_state_publisher
/rviz2
/rviz2
/rviz2_private_140513882059600
/static_transform_publisher
/transform_listener_impl_5605b0dc2500
/transform_listener_impl_563a722cba70
/transform_listener_impl_7fcbf0098ea0

Additional information

Everything is from their respective official repositories. If I remove (or comment out), like below, the name parameter of the Nodes in the launch file, the problem goes away. Why is that? Is this an expected behavior? Should I ignore the warning or stop naming Nodes through the launch file?

Thank you in advance.

def generate_launch_description():
    moveit_config = (
        MoveItConfigsBuilder("moveit_resources_panda")
        .robot_description(file_path="config/panda.urdf.xacro")
        .trajectory_execution(file_path="config/gripper_moveit_controllers.yaml")
        .moveit_cpp(
            file_path=get_package_share_directory("moveit2_tutorials")
            + "/config/moveit_cpp.yaml"
        )
        .to_moveit_configs()
    )
    # MoveItCpp demo executable
    moveit_cpp_node = Node(
        #name="moveit_cpp_tutorial",
        package="moveit2_tutorials",
        executable="moveit_cpp_tutorial",
        output="screen",
        parameters=[moveit_config.to_dict()],
    )

    # RViz
    rviz_config_file = (
        get_package_share_directory("moveit2_tutorials")
        + "/launch/moveit_cpp_tutorial.rviz"
    )
    rviz_node = Node(
        package="rviz2",
        executable="rviz2",
        #name="rviz2",
        output="log",
        arguments=["-d", rviz_config_file],
        parameters=[
            moveit_config.robot_description,
            moveit_config.robot_description_semantic,
        ],
    )

[dhood]

Hi @g-argyropoulos , not a maintainer here, but passed by your question and figure others might too:

This can happen when two nodes exist in a single executable, they will all get the same name remapping, which might explain the behaviour you're seeing. The launch_ros Node concept is a wrapper around an executable and doesn't know how many times rclcpp nodes are created inside, and it'll pass the name remapping to any and all that are inside. HTH