Mixed-Mode Adaptation in Distributed Systems: A Case Study

An adaptation in a distributed system involves changes to multiple processes. Since the adaptation cannot happen atomically (instantaneously), the changes to multiple processes need to be synchronized to ensure correctness of adaptation. The service interruption time and communication overhead during adaptation depend on the synchronization required when changing multiple processes. In this paper we consider mixed-mode adaptation that helps in reducing the synchronization requirements during adaptation, thereby improving the service interruption time and communication overhead. However, there are challenges in mixed-mode adaptation due to overlapping of behavior during adaptation. In this paper, we identify various challenges in mixed-mode adaptation and discuss how we address some of them using a case study.