ROS 2 Node vs Composition (Camera Pub/Sub)

sudo apt install ros-$ROS_DISTRO-image-tools -y
sudo apt install ros-$ROS_DISTRO-composition -y

• check whether image_tools Components exist.

$ ros2 component types
...
image_tools
  image_tools::Cam2Image
  image_tools::ShowImage

• composition usage1 - ros2cli

# terminal 1
ros2 run rclcpp_components component_container
ros2 component list
/ComponentManager

# terminal 2
ros2 component load /ComponentManager image_tools image_tools::Cam2Image

ros2 component unload /ComponentManager 1

• composition usage1 - launch file

ros2 launch cpp_camera_composition eloquent_img_cvt_composition.launch.py 

Composition vs Node standalone

ros2 launch cpp_camera_composition eloquent_camshow_composition.launch.py

ros2 launch cpp_camera_composition eloquent_camshow_node.launch.py 

Benchmark Result

• composition case

CPU Usage (using top)

composition : CPU: ~40% / Mem: 0.7%

standalone nodes 
cam2image_node : CPU: ~20% / Mem: 0.5%
showimage_node : CPU: ~15% / Mem: 0.5%
grayimage_node : CPU: ~15% / Mem: 0.5%