A Token-Based Scheme for Coordinating Decisions in Large-Scale Autonomic Systems

Coordinating decisions in large-scale systems is acknowledged as one of the most challenging aspects of autonomic computing. If control theory is already pushed to its limits by the inevitable decentralised nature of such systems, going large-scale makes things even harder. In this paper, we propose a decentralised token-based scheme for coordinating shared resources allocation in large-scale autonomic systems. In this scheme, each token represents an exclusive access to a share of the resource. Tokens are used and exchanged among autonomic managers to limit their decisions to the resource capacity the tokens they hold at this moment represent. Our token based protocol is meant to provide statistical guarantees on the average total resource usage and the average lateness of node actions due to the coordination. It exposes a set of parameters which we have explored to characterise its fairness and global resource usage on a use case in geotracking. Experiments with the coordination of 10.000 autonomic managers have shown very good results for large spectrum of parameter values and system's regimes.