High CPU load due to joint state broadcaster

[firesurfer]

Describe the bug

I am currently looking into the issue why our ros2control node is consuming 100% cpu load.
For testing purposes I disabled all loaded controllers one by one. As expected the cpu drops a bit for each controller. But for the joint state broadcaster this was rather extreme. I see a change in cpu load for node of ~15-20%.
This is not the case for other controllers that publish messages at the same rate of 500Hz.

We have a rather large amount of joints in our system: 34.

Expected behavior

I would expect that such a simple controller shouldn't consume that much cpu power.

Environment (please complete the following information):

• OS: ubuntu 24.04
• Version Jazzy - 4.16.0

Additional context

When taking a look at the code I would guess at the moment three places that could result in a higher cpu load:

1. there are rather many operations on the map_interface_to_joint_state_ -> but unordered_map should be fast enough
2. mutex operation in the RT publisher
3. Reading the values from the state interfaces -> Not sure if there is any synchronization happening ?

[christophfroehlich]

Strange. To narrow that down, I'd comment the different publishers in the update() method and see if the publishers or the state_interface.get_value() is causing this behavior..

[saikishor]

I highly doubt that it is caused due to the handles. In a synchronous system, mutexes shouldn't do anything. So, as @christophfroehlich suggested try to check with the publishers and see.