feat: Added callback group events executor by jmachowinski · Pull Request #3097 · ros2/rclcpp

jmachowinski · 2026-03-13T17:29:50Z

This commit adds the callback group events executor. It features:

multithreading support
correct handling of sim time
usage of the events subsystem

Description

This moved the events cbg executor from cm_executors into rlcpp mainline.

Did you use Generative AI?

No

rclcpp/include/rclcpp/executors/events_cbg_executor/events_cbg_executor.hpp

rclcpp/include/rclcpp/experimental/executors/events_cbg_executor/events_cbg_executor.hpp

rclcpp/include/rclcpp/executors/events_cbg_executor/events_cbg_executor.hpp

rclcpp/src/rclcpp/executors/events_cbg_executor/events_cbg_executor.cpp

rclcpp/src/rclcpp/experimental/executors/events_cbg_executor/events_cbg_executor.cpp

alsora · 2026-03-15T13:47:51Z

@jmachowinski can you add this to the executor unit-tests?

rclcpp/src/rclcpp/executors/events_cbg_executor/scheduler.hpp

This commit adds the callback group events executor. It features: - multithreading support - correct handling of sim time - usage of the events subsystem Signed-off-by: Janosch Machowinski <[email protected]>

Signed-off-by: Janosch Machowinski <[email protected]>

…ager This code was copied straight from the executor and seems to be a workaround for the multithreaded executor, that breaks in this use case. The correct solution for us is to do the timer->call() from within the worker thread. This fixes a deadlock due to double acquisition of an internal lock within the timer manager. Signed-off-by: Janosch Machowinski <[email protected]>

In case the next timer wakeup time is not changed by an insertion of a timer, don't wake up the timer thread. Signed-off-by: Janosch Machowinski <[email protected]>

jmachowinski · 2026-03-23T14:16:14Z

Pulls: #3097
Gist: https://gist.githubusercontent.com/jmachowinski/f9f71b19f46697be097713df6f9f6016/raw/f0f3fa2b988318178c70a0f1c9f90dbc50321ee8/ros2.repos
BUILD args:
TEST args:
ROS Distro: rolling
Job: ci_launcher
ci_launcher ran: https://ci.ros2.org/job/ci_launcher/18616

Linux
Linux-aarch64
Linux-rhel
Windows

Signed-off-by: Janosch Machowinski <[email protected]>

skyegalaxy

Aside from some spelling nits and a handful of small implementation questions, this is looking great! Very excited to get this over the finish line soon.

rclcpp/include/rclcpp/executors/events_cbg_executor/events_cbg_executor.hpp

skyegalaxy · 2026-03-23T16:13:16Z

rclcpp/src/rclcpp/executors/events_cbg_executor/events_cbg_executor.cpp

+      added_nodes_cpy = added_nodes;
+    }
+
+    // *3 is a rough estimate of how many callback_group a node may have


What would happen in the case where a node might have more than 3 callback groups?

you get slight runtime overhead, as the vector needs to be resized.

skyegalaxy · 2026-03-23T16:15:01Z

rclcpp/src/rclcpp/executors/events_cbg_executor/events_cbg_executor.cpp

+    }
+  }
+
+  // FIXME inform scheduler about remove cbgs


what are the side-effects of leaving this as is and not informing the scheduler here?

rclcpp/src/rclcpp/executors/events_cbg_executor/events_cbg_executor.cpp

rclcpp/test/benchmark/benchmark_executor.cpp

skyegalaxy · 2026-03-23T17:13:23Z

rclcpp/src/rclcpp/executors/events_cbg_executor/timer_manager.hpp

+ * This is needed, as clocks may be deleted during normal operation,
+ * and be don't have a way to create a permanent ros time clock.
+ */
+class ClockConditionalVariable


I think it could be worth eventually merging the functionality of this ClockConditionalVariable variant with the existing one and cutting down on the duplicate code if it's not too complex to do.

rclcpp/src/rclcpp/executors/events_cbg_executor/timer_manager.hpp

mini-1235

Will/should this replace the experimental event executor here?

rclcpp/rclcpp_components/src/component_container_event.cpp

Line 26 in 1e07045

    
           auto exec = std::make_shared<rclcpp::experimental::executors::EventsExecutor>();

Signed-off-by: Janosch Machowinski <[email protected]>

jmachowinski · 2026-03-27T18:26:27Z

Will/should this replace the experimental event executor here?

rclcpp/rclcpp_components/src/component_container_event.cpp

Line 26 in 1e07045

auto exec = std::make_shared<rclcpp::experimental::executors::EventsExecutor>();

yes, that is the idea.

jmachowinski force-pushed the add_cbg_executor branch from 273c322 to 66467b3 Compare March 13, 2026 17:30