concurrency-ros2

name	concurrency-ros2
description	ROS 2 (rclcpp/rclpy) concurrency guidance: executors, callback groups, services/actions/timers, and deadlock-safe patterns. Use when modifying ROS nodes or callbacks.
metadata	{"short-description":"ROS 2 concurrency patterns","requires":["references/concurrency-ros2.md"]}

Purpose

Make ROS callbacks safe, non-blocking where needed, and deadlock-resistant.

When to use

Use this skill when touching:

• rclcpp/rclpy nodes or executors
• callback groups
• services, actions, or timers

How to use

0. Open references/concurrency-ros2.md.
1. Choose executor strategy (SingleThreaded vs MultiThreaded) and justify.
2. Choose callback group layout; explicitly separate blocking/synchronous paths.
3. Identify synchronous service/client calls inside callbacks; apply deadlock rules.
4. Move heavy work off callback threads when needed (worker thread / queue).
5. Add observability hooks for callbacks and queues (length, latency).
6. Define verification (stress + race tooling if multi-threaded).

Output expectation

• Add a ROS2 Concurrency Notes section to the Concurrency Plan.