You're reading the documentation for an older, but still supported, version of ROS 2. For information on the latest version, please have a look at Jazzy.

Building ROS 2 with tracing

Tracing instrumentation is included in the ROS 2 source code, and Linux installations of ROS 2 include the LTTng tracer as a dependency. Therefore, ROS 2 can be traced out-of-the-box on Linux.

However, ROS 2 can be built from source to remove the tracepoints or completely remove the instrumentation. This guide shows how to do that. For more information, see the repository.

Note

This guide only applies to Linux systems.

Prerequisites

Set up your system to build ROS 2 from source. See the source installation page for more information.

Build configurations

The ROS 2 tracing instrumentation is split into two components: function instrumentation and tracepoints. First, a ROS 2 core package (e.g., rclcpp) calls a function provided by the tracetools package. Then, that function triggers a tracepoint, which records data if the tracepoint is enabled at runtime.

By default, if the tracer is not configured to trace or if the tracepoints are not enabled, they will have virtually no impact on the execution. However, the tracepoints can still be removed through a CMake option. Furthermore, the functions can be completely removed through a CMake option, which implies that tracepoints are also removed.

Building without tracepoints

This step depends on whether you are building ROS 2 from source or using ROS 2 binaries (deb packages or binary archive). To remove the tracepoints, (re)build tracetools and set the TRACETOOLS_TRACEPOINTS_EXCLUDED CMake option to ON:

cd ~/ros2_iron
colcon build --packages-select tracetools --cmake-clean-cache --cmake-args -DTRACETOOLS_TRACEPOINTS_EXCLUDED=ON

Building without instrumentation

To completely remove both tracepoints and function calls, build ROS 2 from source and set the TRACETOOLS_DISABLED CMake option to ON:

cd ~/ros2_iron
colcon build --cmake-args -DTRACETOOLS_DISABLED=ON --no-warn-unused-cli

Validating

Validate that tracing is disabled:

cd ~/ws
source install/setup.bash
ros2 run tracetools status

It should print out:

Tracing disabled

If something else is printed, then something went wrong.