[ros-users] [Discourse.ros.org] [Next Generation ROS] Maximum amount of publisher / subscriptions per node

[William Woodall]

[quote="firesurfer, post:3, topic:1391"]
As far as I can see every node creates some topics for interacting with a parameter server by default. Can I somehow disable this behaviour ?
[/quote]

Not currently. Right now this publisher is always created:

https://github.com/ros2/rclcpp/blob/master/rclcpp/src/rclcpp/node_interfaces/node_parameters.cpp#L40-L45

We've often talked about adding an option to the node constructor which would avoid this, but we've always stopped short because we wanted to implement a proper way to pass lots of options to a node constructor other than lots of arguments, i.e. some sort of rclcpp specific node options struct.

However, if you proposed a new argument to the node constructor which disabled this topic, then I'd consider it for merge in the meantime.

[quote="firesurfer, post:3, topic:1391"]
I also have another implementation specific question: Is it possible to have a subscription call multiple callbacks?
[/quote]

Not right now, but we also would like to do that at some point. You can implement it trivially though, by creating a single callback for the subscription which then iterates over a list of callbacks, calling each in turn.

We thought about multiple callbacks for single subscriber in the context of multi threading and executors and callback groups but that's quite a bit more complicated and needs some more thought I think.






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