层次式体系结构下一种似然时标系统

A Plausible Timestamp System in Hierarchical Architecture

当前,分布式系统具有越来越大的规模,而且可能层次地分布在广域网上,这些属性增加了保证分布式系统中时序关系的难度.向量时钟可以准确地探测事件间的时序关系,但是向量时钟的维度与节点数相同,就引起了效率和可扩展性问题.该文提出了层次体系结构下确定分布式系统时序关系的一种优化解决方案.首先给出了分布式系统的一种层次式体系结构,其中独立的子组通过代理进程互连,组成集群完成特定目标;在这种结构中,采用"分而治之"的策略,提出了一种似然时标系统,其特点是消息传输时的时间标签仅仅是系统时标的一部分.该时标系统能够探测大规模分布式系统中消息间的因果关系,而且具有较好的效率和可扩展性.

Currently, in distributed systems there are more and more processes which are hierarchically distributed in the wide area network, which make it hard to realize the causality in the distributed systems. In a distributed system with N sites, the precise detection of causal relationships between events can only be done with vector clocks of size N. This gives rise to scalability and efficiency problems for vector clocks. In this paper, a kind of hierarchical architecture is described in which proxy process is used to exchange messages between the subgroups and global group can be composed to achieve some objectives. A plausible timestamp system is presented using divide-and-conquer approach, in which only a part of the timestamp is attached to the message as the tag whenever the message is transmitted. The timestamp system allows to detecting causality between events in a large distributed system with high degree of accuracy, enhancing the scalability of the system and minimizing the affection because of adding or reducing federates.