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99 Work/0 OneSec/OneSecNotes/30 Engineering Skills/Robotics/ROS2/ROS2 - Debugging.md

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+[[ROS2]] is a bit tedious to debug, because it is inherently asynchronous and multi threaded.
+
+A good way is to use VSCode for example like this:
+https://gist.github.com/JADC362/a4425c2d05cdaadaaa71b697b674425f
+
+As always the nav2 library is a good place for resources: [get backtrace explanation](https://navigation.ros.org/tutorials/docs/get_backtrace.html).
+## Requirements
+In order to run this we need to install gdbserver: `sudo apt install gdbserver`
+## Launch Files
+In the launch file, when adding a Node, add a `prefix="gdbserver localhost:3000"`:
+```python
+Node(
+	package='nav3_controller',
+	executable='controller_server',
+	output='screen',
+	respawn=use_respawn,
+	respawn_delay=2.0,
+	parameters=[configured_params],
+	prefix='gdbserver localhost:3000',
+	arguments=['--ros-args', '--log-level', log_level],
+	remappings=remappings + [('offboard_cmd', 'offboard_velocity_cmd')]
+)
+```
+
+This will create gdb as a server. Now we need to configure VSCode to attach to this debug session (as explained [here](https://answers.ros.org/question/267261/how-can-i-run-ros2-nodes-in-a-debugger-eg-gdb/)) add a new launch configuration like this:
+```json
+{
+    "version": "0.2.0",
+    "configurations": [
+        {
+            "name": "C++ Debugger",
+            "request": "launch",
+            "type": "cppdbg",
+            "miDebuggerServerAddress": "localhost:3000",
+            "cwd": "/",
+            "program": "[build-path-executable]"
+        }
+    ]
+}
+```
+