Use ParamListener::try_get_params to Avoid Blocking in Real-Time Contexts

[KentaKato]

Due to the potential blocking risk associated with ParamListener::get_params, it is advisable to avoid its usage in real-time contexts. The method, defined here, can lead to delays that are unsuitable for time-sensitive operations.

As an alternative, I have switched to using ParamListener::try_get_params, which does not carry the risk of blocking. This non-blocking approach ensures better performance in real-time scenarios. You can find the implementation here.

[saikishor]

@KentaKato Thank you for propagating these nice changes into the ros2_controllers.

We would need to wait for the generate_parameter_library to be released in the distros before merging this.

Thank you

[bmagyar]

Started a "tracking issue" for this ;)

PickNikRobotics/generate_parameter_library#209

[KentaKato]

@saikishor @bmagyar Thank you!

[christophfroehlich]

GPL got released, but something is very strange now with the JTC tests in the CI. Severals jobs fail with a segfault, and others have errors like test_success_multi_point_with_velocity_sendgoal in semi-binary (rolling, main). I ran the tests locally, here

5: [  FAILED  ] OnlyEffortTrajectoryControllers/TestTrajectoryActionsTestParameterized.test_success_single_point_with_velocity_sendgoal/0, where GetParam() = ({ "effort" }, { "position", "velocity" }) (2026 ms)

@KentaKato could you have a look please?

[KentaKato]

@christophfroehlich

Although I haven't been able to reproduce this in my environment and haven't had time to thoroughly investigate it yet, I think the following logs are abnormal:

2024-10-29T21:07:04.7515029Z 5: [ERROR] [1730235957.984823612] [tolerances]: State tolerances failed for joint 0:
2024-10-29T21:07:04.7515356Z 5: [ERROR] [1730235957.984917837] [tolerances]: Position Error: 0.000000, Position Tolerance: 0.000000
2024-10-29T21:07:04.7515679Z 5: [ERROR] [1730235957.984965445] [tolerances]: Velocity Error: 0.015223, Velocity Tolerance: 0.000000
2024-10-29T21:07:04.7516030Z 5: [WARN] [1730235957.984997345] [test_joint_trajectory_controller]: Aborted due to state tolerance violation

This is because, according to tolerances.hpp (link), tolerance errors should only be evaluated when state_tolerance > 0.0.

I'll look into this further from tomorrow onward.

[bmagyar]

There was one set of tests passing on the previous run of the CI so I'm suspecting flakiness, I poked the CI again, let's see the results...