Achieving Predictable Timer Management under Varying Workload Conditions in ROS 2

ROS 2 has become a widely adopted framework for developing modular and distributed robotic systems, enabling the construction of complex processing chains that are typically triggered by periodic timers and interconnected through message-passing callbacks. While prior research has focused on analyzing end-to-end latency, little attention has been paid to the workload release mechanisms, particularly the behavior of timer-triggered processing chains under varying system loads. This gap is critical, as improper handling of timer activation can compromise real-time guarantees. This paper presents a comprehensive analysis of timer management in ROS 2 executors and reveals key limitations in their ability to satisfy the timing needs of two distinct classes of processing chains: non-skippable chains that demand strict periodic release, and skippable chains that can tolerate instance dropping. To address these shortcomings, we propose a new timer management mechanism that decouples activation, scheduling, and release control. Our approach provides reliable release control for non-skippable chains while adaptively shedding load from skippable ones. Experimental results demonstrate that the proposed design significantly improves predictable system performance across diverse and dynamic workload conditions. © 2026 IEEE.