CallbackIsolatedExecutor

The CallbackIsolatedAgnocastExecutor assigns a dedicated OS thread to each CallbackGroup, enabling per-callback scheduling control (policy, priority, CPU affinity). It is the Agnocast-compatible version of callback_isolated_executor.

Why

Standard ROS 2 executors share threads across callbacks — you cannot control which callback runs on which CPU or at what priority.

``` Standard Executor: CallbackIsolatedExecutor:

CallbackGroup A ─┐ CallbackGroup A → Thread (FIFO, prio=90, CPU0) CallbackGroup B ─┼→ Thread Pool CallbackGroup B → Thread (FIFO, prio=80, CPU1) CallbackGroup C ─┘ CallbackGroup C → Thread (CFS, nice=0)

No per-callback control Full OS-level scheduling control ```

With CallbackIsolatedExecutor, each CallbackGroup maps to exactly one OS thread. Scheduling is handled entirely by the Linux kernel — you directly assign SCHED_FIFO, SCHED_RR, SCHED_DEADLINE, or CFS parameters per callback.

For the design rationale and evaluation, see the RTAS 2025 paper: Middleware-Transparent Callback Enforcement in Commoditized Component-Oriented Real-time Systems.

Note

CallbackIsolatedAgnocastExecutor does not require agnocast-kmod or agnocast-heaphook. If you only want per-callback scheduling control without Agnocast's zero-copy IPC, you can use the executor on its own — just install the agnocastlib ROS package.

Naming

	Original	Agnocast Version
Package	callback_isolated_executor	agnocast_components or agnocastlib
Executor Class	CallbackIsolatedExecutor	agnocast::CallbackIsolatedAgnocastExecutor
Container Executable	component_container_callback_isolated	agnocast_component_container_cie
Thread Configurator	cie_thread_configurator	agnocast_cie_thread_configurator

Executor Variants

Executor	Handles ROS 2 Callbacks	Handles Agnocast Callbacks	Use Case
CallbackIsolatedAgnocastExecutor	Yes	Yes	Stage 1 or mixed Stage 1/2
AgnocastOnlyCallbackIsolatedExecutor	No	Yes	Stage 2 only

Pages

• Integration Guide — How to introduce CallbackIsolatedExecutor and set up the thread configurator
• YAML Specification — Complete reference for the thread configuration file
• Non-ROS Threads — Managing scheduling for threads outside the ROS 2 executor
• Tutorial — End-to-end walkthrough with a sample application