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Added tracepoint for rclcpp_take event when message loaning is used#3103

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nightduck:tracing_rclcpp_take_zero_copy
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Added tracepoint for rclcpp_take event when message loaning is used#3103
nightduck wants to merge 1 commit intoros2:rollingfrom
nightduck:tracing_rclcpp_take_zero_copy

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@nightduck nightduck commented Mar 18, 2026

Description

It's difficult to fully trace a system when using zero-copy because the rclcpp_take tracepoint is not invoked. This corrects for that.

Is this user-facing behavior change?

No

Did you use Generative AI?

No

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@nightduck nightduck marked this pull request as draft March 18, 2026 09:24
@jmachowinski
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jmachowinski commented Mar 18, 2026

I would rather add the tracepoint to rcl_take_loaned_message, as the tracepoint for rcl_take is also in rcl.
This would also fix rclpy tracing as well.

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nightduck commented Mar 18, 2026 •
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When a message take is performed, there's 3 trace points called: rclcpp_take, rcl_take, and rmw_take. I'm already working on the last 2 with PRs in other packages. But rclcpp_take doesn't get triggered when subscription->can_loan_messages() is true

@nightduck nightduck marked this pull request as ready for review March 18, 2026 15:41
christophebedard
christophebedard approved these changes Mar 31, 2026
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LGTM.

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christophebedard commented Mar 31, 2026

@Mergifyio rebase

@nightduck @christophebedard
Added tracepoint
1248b50 
Signed-off-by: Oren Bell <oren.bell@autonomous-teaming.ai>
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mergify bot commented Mar 31, 2026

rebase

✅ Branch has been successfully rebased

@christophebedard christophebedard force-pushed the tracing_rclcpp_take_zero_copy branch from 958f282 to 1248b50 Compare March 31, 2026 00:13
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christophebedard commented Mar 31, 2026 •
edited by ahcorde
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Pulls: #3103
Gist: https://gist.githubusercontent.com/christophebedard/ccae62050901f0a4df3b5fcf935bb255/raw/d8261a9291ede3e844d81bb8a37fca171aa81105/ros2.repos
BUILD args: --packages-above-and-dependencies rclcpp test_tracetools
TEST args: --packages-above rclcpp test_tracetools
ROS Distro: rolling
Job: ci_launcher
ci_launcher ran: https://ci.ros2.org/job/ci_launcher/18739

  • Linux Build Status
  • Linux-aarch64 Build Status
  • Linux-rhel Build Status
  • Windows Build Status

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christophebedard commented Mar 31, 2026

Yeah, there are multiple tracepoints, at different layers: rclcpp, rcl, and rmw.

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@christophebedard christophebedard christophebedard approved these changes

@fujitatomoya fujitatomoya fujitatomoya approved these changes

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@nightduck @jmachowinski @christophebedard @fujitatomoya