Revision history [back]

To know what granularity is good for your nodes, keep in mind that a ROS node first job is to make processes communicate together. Having multiple processes allow you to have several independent algorithms running in parallel. However, processes are heavy objects and you cannot have a lot of them at the same time. To run thousands of tasks in parallel alternative techniques such as threading or coroutine are more suitable.

On top of that there is an overhead when you are communicating data from one node to another. ROS relies on the network to do this. This induces additional computation compared to a single-process algorithm.

To reduce this overhead and reduce the number of concurrent processes running, ROS supports nodelets. Nodelets are a way to aggregate several ROS nodes into one single process. This allow you to run as many nodes as you want into one process while removing the communication overhead.

However, using this model still has a cost as implementing nodelets is more challenging than challenging a normal node. In this case, think about the development cost of your application, the additional feature that ROS may or may not provide you and try to avoid over-engineering your solution.

To know what granularity is good for your nodes, keep in mind that a ROS node first job is to make processes communicate together. Having multiple processes allow you to have several independent algorithms running in parallel. However, processes are heavy objects and you cannot have a lot of them at the same time. To run thousands of tasks in parallel alternative techniques such as threading or coroutine are more suitable.

On top of that there is an overhead when you are communicating data from one node to another. ROS relies on the network to do this. This induces additional computation compared to a single-process algorithm.

To reduce this overhead and reduce the number of concurrent processes running, ROS supports nodelets. Nodelets are a way to aggregate several ROS nodes into one single process. This allow you to run as many nodes as you want into one process while removing the communication overhead.

However, using this model still has a cost as implementing nodelets is more challenging than challenging a normal node. In this case, think about the development cost of your application, the additional feature that ROS may or may not provide you and try to avoid over-engineering over-engineer your solution.