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A default colcon build of MoveIt 2 (Jazzy, 41 packages) was killed at an 8GB cap and peaked at 8.7GiB at 16GB; a sequential build peaked at 2.4GiB and finished at 4GB.

rclpy rate.sleep() waits for a timer callback only an executor runs: spin in another thread or use MultiThreadedExecutor(num_threads=2).

Split Foo[] into uint64[] + uint32[]: rclpy publish() of 10,000 elements dropped from about 10 ms to 0.25 ms on ROS 2 Jazzy.

Your env returns the same NumPy array every step, so every buffer slot holds the latest value; return self._q.copy(), not obs[:] or np.asarray(obs).

Default colcon build of Nav2 failed at 4GB and peaked at 7.8GiB of 8GiB; a sequential build peaked at 2.7GiB and finished at 4GB.

If either node has ROS_AUTOMATIC_DISCOVERY_RANGE=OFF, nothing connects; across hosts, LOCALHOST also needs ROS_STATIC_PEERS on one side.

As of October 2026, Iron is past EOL and Humble has 7 months left; for longer projects use Jazzy (31 months, Ubuntu 24.04) or Lyrical (55).

In a fresh shell, install/local_setup.bash adds only your overlay and no ros2 command; install/setup.bash also loads the underlay it was built on.

A backwards ROS 2 static transform with no rotation puts the child exactly 2x the offset away; with rotation the ratio varies, and under odom the tree breaks.

In a ROS 2 Jazzy container, /clock held real time factor 1.0 while a 100 Hz callback missed its 10 ms deadline 20 times in 5 s. RTF doesn’t see deadlines.