ROS nodes can be debugged as regular programs. They run as a process in the operating 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 memcheck 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 simply run the command through gdb in the following way:

    $ gdb rosrun chapter3_tutorials example1
  

In the following sections, we will explain how to call these tools for an ROS node to overcome this issue. Later, we will see how to add logging messages to our code in order to make it simple to diagnose problems; in practice, using logging messages helps to diagnose basic (and not so basic) problems without the need to debug the binaries. Similarly, we will discuss ROS introspection tools, which allow you to easily detect broken connections between nodes. Finally, even though we will provide a bottom-up overview, in practice we usually follow a top-down approach to diagnosing issues.