Ros2's colcon will build the packages in your workspace individually, in topological order of the dependency DAG. This is a completely insane way to structure a

Ros2's colcon will build the packages in your workspace individually, in topological order of the dependency DAG. This is a completely insane way to structure a c++ build because it destroys the innate parallelism of the compilation process. The build system for ros1, catkin, didn't have this problem because it turned all your packages into a single cmake build. Just one of the many ways that ros2 was a regression from ros1.