ROS2-Multithreaded-Executor-Starvation-Examples

The following content are the example systems in of the multi-threaded in ROS 2 that show starvation, i.e., tasks may never be executed. These results are based on the paper "Thread Carefully: Preventing Starvation in the ROS 2 Multithreaded Executor" by Teper et al. in EMSOFT 2024.

Setup

The following steps help to setup and run the experiments.

Requirements

Install Docker Engine

Install Visual Studio Code

Startup

There are two options for the startup of the container.

Option 1: Start the Container with Visual Studio Code

In Visual Studio Code, install the Docker and Dev Containers extensions.

Build and open the container.

Option 2: Start the Container with Docker

Run the following command in a terminal that is in the current folder's directory:

docker build -t ros2-application .devcontainer/

Start the container using the following command:

docker run --network host -it -v .:/home/vscode/workspace ros2-application

Experiments

Start and enter the Docker or Dev Container.

Build

To build the ROS 2 packages, you need to build them first. Run the following commands based on your environment.

Docker

"cd packages && colcon build --symlink-install"

Dev Container

Press Ctrl+Shift+P, type "Run Task", press Enter, and select "ROS2-Build"

Run

To run the experiments, use the following commands:

Docker

Example 4:

source packages/install/setup.bash && ros2 launch starvation_examples launch_starvation_examples.launch.py example_number:=4

Example 5:

source packages/install/setup.bash && ros2 launch starvation_examples launch_starvation_examples.launch.py example_number:=5

Example 6:

source packages/install/setup.bash && ros2 launch starvation_examples launch_starvation_examples.launch.py example_number:=6

Dev Container

Press Ctrl+Shift+P, type "Run Task", press Enter, and select from the following options:

RUN-Example-4
RUN-Example-5
RUN-Example-6

Output

While the experiment is running, you will see two things.

During startup, there will be the following messages

[starvation_examples]: Starvation Node Startup
[starvation_examples]: Example Number: 4
[starvation_examples]: Timer 2 should never be executed
[starvation_examples]: Starvation Node Ready
[starvation_examples]: Starting execution

After that, the following messages will appear (depending on the example number, the number of the timers may change):

[starvation_examples]: Timer 1 executes
[starvation_examples]: Timer 3 executes

For starvation, you need to check whether or not the timer that was specified during startup is never part of the output messages after the execution starts.

As each timer has a maximum period of 1000ms, it is usually enough to run the experiment for 10 seconds.

The experiments show that the multi-threaded executor suffers from starvation, as some tasks are never executed.