Demand-Driven Weak Clock Synchronization for Distributed Applications

It is often required to analyze the behavior and reliability of large distributed systems before deploying them. This task relies on the existence of a dependency graph. The dependency graph can be constructed according to the blueprint of the system (if available) or by measuring runtime messages. To construct such a graph by measuring the runtime messages, the clocks on different nodes must be weakly synchronized. The causality violation must be detected and corrected. In this paper, we study the problem of weak synchronization. A demand-drive weak clock synchronization protocol is proposed. The proposed protocol consists of 3 components: (1) ldquoproberdquo module, (2) ldquodetectionrdquomodule and (3) ldquosynchronizationrdquo module. The proposed protocol is light-weighted and has very small synchronization overhead. It has almost no effect on the actual running applications. Preliminary experimental results validate the effectiveness of the proposed approach.