ROS nodes can be debugged as regular programs. They run as a process in the operative system and have a PID. Therefore, you can debug them as with any program using standard tools, such as gdb. Similarly, you can check for memory leaks with valgrind or profile the performance of your algorithm with callgrind. However, remember that in order to run a node, you must run the following command:

$ rosrun chapter3_tutorials example1

Unfortunately, you cannot run the command in the following way:

$ gdb rosrun chapter3_tutorials example1

In the next sections, we will explain how to call these tools for an ROS node to overcome this issue. Later, we will see how to add a logging message to our code in order to make it simple to diagnose problems that, in practice, helps to diagnose basic problems even without debugging the binaries. Similar, later on, we will discuss ROS introspection tools that allow detecting broken connections between nodes easily. Therefore, although here we...