Improving Scalability and Reward of Utility-Driven Self-Healing for Large Dynamic Architectures

TL;DR

This paper introduces a hybrid rule-based and utility-driven self-healing approach for large dynamic software architectures, achieving scalable, optimal repairs without expensive optimization, validated through experiments on real-world failure logs.

Contribution

It proposes a novel adaptation scheme combining rule-based and utility-driven methods, enabling scalable and optimal self-healing in large systems.

Findings

The approach scales well with large architectures.

It achieves higher reward than static rule-based methods.

It maintains near-optimal performance compared to full utility optimization.

Abstract

Self-adaptation can be realized in various ways. Rule-based approaches prescribe the adaptation to be executed if the system or environment satisfies certain conditions. They result in scalable solutions but often with merely satisfying adaptation decisions. In contrast, utility-driven approaches determine optimal decisions by using an often costly optimization, which typically does not scale for large problems. We propose a rule-based and utility-driven adaptation scheme that achieves the benefits of both directions such that the adaptation decisions are optimal, whereas the computation scales by avoiding an expensive optimization. We use this adaptation scheme for architecture-based self-healing of large software systems. For this purpose, we define the utility for large dynamic architectures of such systems based on patterns that define issues the self-healing must address. Moreover, we use pattern-based adaptation rules to resolve these issues. Using a pattern-based scheme to define the utility and adaptation rules allows us to compute the impact of each rule application on the overall utility and to realize an incremental and efficient utility-driven self-healing. In addition to formally analyzing the computational effort and optimality of the proposed scheme, we thoroughly demonstrate its scalability and optimality in terms of reward in comparative experiments with a static rule-based approach as a baseline and a utility-driven approach using a constraint solver. These experiments are based on different failure profiles derived from real-world failure logs. We also investigate the impact of different failure profile characteristics on the scalability and reward to evaluate the robustness of the different approaches.