MutliThreadedExecutor update rate is unstable

[buschbapti]

I have tried following the ros2_control_demos and made some testing to push the frequency of the update rate. Turned out that hz the /joint_states topic produces inconsistent behaviors with the receiving frequency sometime 10 time slower than expected. I know you are using MultiThreadedExecutor and to my experience I had this issue on a publisher on my own. I initially thought it was because I was using Docker and there was some configuration to do but turns out I can reproduce the same on a desktop installation.

I have opened an issue #1487 on rclcpp repository because I do think it comes from the MultiThreadedExecutor that is not reliable. Have you ever had the same issue? Did you solve it by using some specific things like real time kernel?

[buschbapti]

Ok good progress has been made on rclcpp side. It has been confirmed that this problem comes from the MultiThreadedExecutor and a patch has been found. I have tested it and the solution works for the demo as well and solves this issue. Do you want me to close this issue or should I keep it open until the patch has been pushed to rclcpp?

[destogl]

Hi @buschbapti,
Thanks for the detailed analysis! I would keep it open for now, since probably other people will have it also.

So it seems this will be solved in galactic?

[destogl]

This is related to PR ros2/rclcpp#1168

@bmagyar: can you rename this to "MutliThreadedExecutor update rate is unstable" (or something similar?

[bmagyar]

This is a duplicate of #277, closing in favour