This small example shows the steps to follow to trace a SMACC2 library. First, make sure that smacc and tracetools installed (or built in your workspace) in your system.

See README.md for setting up a SMACC workspace.

Setting up LTTng

sudo apt-add-repository ppa:lttng/stable-2.12
sudo apt-get update
sudo apt-get install lttng-tools lttng-modules-dkms liblttng-ust-dev

Create and add your user to a new tracing group

newgrp tracing

sudo usermod -aG tracing `whoami`

Reboot or log out and back in to your user to update user groups

sudo su $USER

Install Python packages for reading and setting up tracing sessions

sudo apt-get install python3-babeltrace python3-lttng

In your SMACC2 workspace, install the following tracing repos.

wget https://gitlab.com/ros-tracing/ros2_tracing/raw/master/tracing.repos

vcs import src < tracing.repos

Finally build your workspace

colcon build

source install/setup.bash

Then start your smacc application:

ros2 launch sm_three_some sm_three_some.launch

Once the application is running you can check if the tracepoints are available via the lttng command:

lttng list --userspace

You should get the list of nodes with tracepoints available. Below it is shown a chunk of the output got with that command, we see how the smacc and the default ros2 tracepoint are available:

[...]
ID: 1663722 - Name: /home/geus/Desktop/smacc_tracing/install/sm_three_some/lib/sm_three_some/sm_three_some_node
      ros2:smacc2_client_behavior_on_exit_end (loglevel: TRACE_DEBUG_LINE (13)) (type: tracepoint)
      ros2:smacc2_client_behavior_on_exit_start (loglevel: TRACE_DEBUG_LINE (13)) (type: tracepoint)
      ros2:smacc2_client_behavior_on_entry_end (loglevel: TRACE_DEBUG_LINE (13)) (type: tracepoint)
      ros2:smacc2_client_behavior_on_entry_start (loglevel: TRACE_DEBUG_LINE (13)) (type: tracepoint)
      ros2:smacc2_state_onExit_end (loglevel: TRACE_DEBUG_LINE (13)) (type: tracepoint)
      ros2:smacc2_state_onExit_start (loglevel: TRACE_DEBUG_LINE (13)) (type: tracepoint)
      ros2:smacc2_state_onEntry_end (loglevel: TRACE_DEBUG_LINE (13)) (type: tracepoint)
      ros2:smacc2_state_onEntry_start (loglevel: TRACE_DEBUG_LINE (13)) (type: tracepoint)
      ros2:smacc2_state_onRuntimeConfigure_end (loglevel: TRACE_DEBUG_LINE (13)) (type: tracepoint)
      ros2:smacc2_state_onRuntimeConfigure_start (loglevel: TRACE_DEBUG_LINE (13)) (type: tracepoint)
      ros2:smacc2_state_update_end (loglevel: TRACE_DEBUG_LINE (13)) (type: tracepoint)
      ros2:smacc2_state_update_start (loglevel: TRACE_DEBUG_LINE (13)) (type: tracepoint)
      ros2:smacc2_event (loglevel: TRACE_DEBUG_LINE (13)) (type: tracepoint)
      ros2:spinOnce (loglevel: TRACE_DEBUG_LINE (13)) (type: tracepoint)
      ros2:callback_end (loglevel: TRACE_DEBUG_LINE (13)) (type: tracepoint)
      ros2:callback_start (loglevel: TRACE_DEBUG_LINE (13)) (type: tracepoint)
      ros2:rclcpp_callback_register (loglevel: TRACE_DEBUG_LINE (13)) (type: tracepoint)
      ros2:rclcpp_timer_callback_added (loglevel: TRACE_DEBUG_LINE (13)) (type: tracepoint)
      ros2:rcl_timer_init (loglevel: TRACE_DEBUG_LINE (13)) (type: tracepoint)
      ros2:rcl_client_init (loglevel: TRACE_DEBUG_LINE (13)) (type: tracepoint)
      ros2:rclcpp_service_callback_added (loglevel: TRACE_DEBUG_LINE (13)) (type: tracepoint)
      ros2:rcl_service_init (loglevel: TRACE_DEBUG_LINE (13)) (type: tracepoint)
      ros2:rclcpp_subscription_callback_added (loglevel: TRACE_DEBUG_LINE (13)) (type: tracepoint)
      ros2:rclcpp_subscription_init (loglevel: TRACE_DEBUG_LINE (13)) (type: tracepoint)
      ros2:rcl_subscription_init (loglevel: TRACE_DEBUG_LINE (13)) (type: tracepoint)
      ros2:rcl_publisher_init (loglevel: TRACE_DEBUG_LINE (13)) (type: tracepoint)
      ros2:rcl_node_init (loglevel: TRACE_DEBUG_LINE (13)) (type: tracepoint)
      ros2:rcl_init (loglevel: TRACE_DEBUG_LINE (13)) (type: tracepoint)
      [...]

Now lets start a recording session. We use a custom command trace.sh, it is essentially an extended version of ros2 trace but also adding the smacc tracepoints to be recorded:

ros2 run smacc2 trace.sh

We press a key, record some seconds and then stop the recording pressing again some key:

ros2 run smacc2 trace.sh
UST tracing enabled (33 events)
kernel tracing enabled (4 events)
context (3 names)
writing tracing session to: /home/geus/.ros/tracing/session-20210528232348
press enter to start...
press enter to stop...
stopping & destroying tracing session

We can check the tracing database using the babeltrace tool or the tracecompass tool. In our case we use trace compass. Importing the data from the tracing output directory.