fix ObstacleLayer not working due to #2489

[gezp]

Signed-off-by: zhenpeng ge zhenpeng.ge@qq.com

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Basic Info

Info	Please fill out this column
Ticket(s) this addresses	(add tickets here #3014)
Primary OS tested on	(Ubuntu22.04)
Robotic platform tested on	(gazebo simulation of turtlebot3)

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Description of contribution in a few bullet points

Obstacle Layer not working (the scan data isn't subscribed by Obstacle Layer), becasue observation_subscribers_->subsciber() failed when ObstacleLayer::activate() is called since #2489

• use active_ flag instead of subscibe() and unsubscibe() (refer to https://github.com/ros-planning/navigation2/blob/main/nav2_amcl/src/amcl_node.cpp#L614)

i'm not sure the side effect of this change, maybe we could have a better solution.

Description of documentation updates required from your changes

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Future work that may be required in bullet points

For Maintainers:

• Check that any new parameters added are updated in navigation.ros.org
• Check that any significant change is added to the migration guide
• Check that any new features OR changes to existing behaviors are reflected in the tuning guide
• Check that any new functions have Doxygen added
• Check that any new features have test coverage
• Check that any new plugins is added to the plugins page
• If BT Node, Additionally: add to BT's XML index of nodes for groot, BT package's readme table, and BT library lists

[mergify]

@gezp, please properly fill in PR template in the future. @SteveMacenski, use this instead.

• Check that any new parameters added are updated in navigation.ros.org
• Check that any significant change is added to the migration guide
• Check that any new features OR changes to existing behaviors are reflected in the tuning guide
• Check that any new functions have Doxygen added
• Check that any new features have test coverage
• Check that any new plugins is added to the plugins page
• If BT Node, Additionally: add to BT's XML index of nodes for groot, BT package's readme table, and BT library lists

[gezp]

CC @jwallace42

[SteveMacenski]

If callback groups aren't being respected, how does bypassing the unsubscribe help? Per rclcpp issue thread

[gezp]

If callback groups aren't being respected, how does bypassing the unsubscribe help? Per rclcpp issue thread

maybe I don't get your meaning，the problem is caused by subscribe(), not related to unsubscribe() .

[SteveMacenski]

ros2/rmw_fastrtps#619 supposedly fixes it and is merged!

[dcconner]

Humble binaries as of 18-Oct still have this issue. Switching to Cyclone seems to fix. Just commenting here for others that might be trying to track down issue