[rclcpp_components] Enable intra-process comm via LoadNode request.

[hidmic]

Look for a 'use_intra_process_comms' boolean in extra_arguments.

[hidmic]

We don't do much testing for rclcpp_components, do we? The most relevant one, test_component_manager_api , consistently fails and I bet it has to do with repeated node bring up / tear down.

I plan to test this manually, but until ros2/rcl#508 and friends are in ros2 component is broken.

[mjcarroll]

I believe that it recently went from flaky to more consistently failing, I opened an issue here: #863

[mjcarroll]

LGTM, thanks Mich!

[hidmic]

Running CI up to rclcpp_components:

• Linux
• Linux-aarch64
• OSX
• Windows

[iluetkeb]

@hidmic Is there an example for how to use this in a launch file?

btw, I'm sure you guys must have plenty of example launch files that the community could have a look at, to figure out how to actually use launch properly. putting them somewhere would be awesome.

Edit: This is not in dashing, yet, right?

[ZhenshengLee]

@hidmic Is there an example for how to use this in a launch file?

btw, I'm sure you guys must have plenty of example launch files that the community could have a look at, to figure out how to actually use launch properly. putting them somewhere would be awesome.

@iluetkeb
the extra_arguments is here, define a ComposableNode with this parameter I guess.

https://github.com/ros2/launch_ros/blob/79f783b1fe5e06d71737e2955a8f4eb9c4f3923c/launch_ros/launch_ros/descriptions/composable_node.py#L39-L60

Thanks.