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Default callback group?

asked 2020-12-09 18:53:59 -0500

galaxee gravatar image

http://docs.ros2.org/latest/api/rclpy... I saw in the definition for action clients that if no callback group was defined that the node's default callback group is used. How can I find what this is?

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answered 2020-12-11 15:22:27 -0500

clalancette gravatar image

The default callback group is just an internal, MutuallyExclusive callback group. That means that one, and only one of the callbacks within the group can run simultaneously. This is the safest configuration to run in, though it may not be the highest performance.

To directly answer your question, I don't think we have a way to access the default callback group. What are you trying to do that you need it?

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Thanks! I don't need to access the default callback group, I just didn't know where to look to see what the default callback group was.

Just to make sure I understand, does this mean that if for one node, you use a MultiThreadedExecutor but a MutuallyExclusiveCallbackGroup, it's not different from using a SingleThreadedExecutor?

galaxee gravatar image galaxee  ( 2020-12-11 15:30:44 -0500 )edit

Ah, no worries. I had to go grubbing through the source to find it, but it is created here: https://github.com/ros2/rclcpp/blob/9...

clalancette gravatar image clalancette  ( 2020-12-11 15:38:38 -0500 )edit

Thanks! Sorry I edited my comment but not sure if you saw the edit. Does this mean that if for one node, you use a MultiThreadedExecutor but a MutuallyExclusiveCallbackGroup, it's not different from using a SingleThreadedExecutor?

galaxee gravatar image galaxee  ( 2020-12-11 15:45:15 -0500 )edit

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Asked: 2020-12-09 18:53:59 -0500

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Last updated: Dec 11 '20