What is a "ROS2 Process" with regards to DDS Participants?
On "The ROS_DOMAIN_ID" page of the ROS2 Foxy docs, it says the following:
"For each ROS 2 process running on a computer, one DDS “participant” is created. Since each DDS participant takes up two ports on the computer, running more than 120 ROS 2 processes on one computer may spill over into other domain IDs or the ephemeral ports."
What exactly is considered a ROS 2 process? Is it every node? Every sub/pub? Or each time you call rclcpp::init()?
I have an application that uses ROS for some features and looking into using different domain IDs in each instance of the app to ensure that the two instances do not interfere. However, I would like to know if there is any possibility of the two instances' ports overlapping.