A non-blocking locking method and performance evaluation on network of workstations

A network of workstation(NOW) can act as a single and scalable powerful computer by building a paralle and distributed computing platform on top of it.WAKASHI is such a platform system that supports persitent object management and makes full use of resources of NOW for high perforance transaction processing,One of the main difficulties to overcome is the bottleneck caused by concurrency control mechanism.Therefore,a non-bloking locking method is designed,by adopting several novel techniques to make it outperform the other typical locking methods such as 2PL:1) an SDG (Semantic Dependency Graph)based non-blocking locking protocol for fast transaction scheduling;2) a nmassively virtual memory based backup-page undo algorithm for fast restart;and 3) a multi-processor and multi-thread based transaction manager for fast execution.The new mechanisms have been implemented in WAKASHI and the performance comparison experiments have been implemented in WAKASHI and the performance comparison experiments with 2PL and DWDL have been done.The results show that the new method can outperform 2PL and DWDL under certain conditons.This is meaningful for choosing effective concurrency control mechanisms for improving transaction-rpocessing performance in NOW environments.     

一个NT平台上分布式对象数据库服务器系统

FISH系统是一个用于支持先进应用(如GIS,EC,CIMS)的新一代分布式对象数据库系统.该系统采用了许多新颖技术,如DSVM(distributed shared virtual memory)、持久堆、页式对象、透明锁、紧凑提交等.重点介绍了该系统的总体结构和设计思想,特别是FISH系统在Windows NT上实现所涉及的底层技术,包括内存映射、共享内存、远程过程调用、多线索连接、页面故障处理等.基于OO7的性能测试表明,FISH系统在NT机群环境下取得了与在分布式UNIX环境下同样高的分布执行效率     

将政府化身于网络上

介绍了美国、英国的电子政务之后,作为系列报道最后一期,本期内容是介绍日本的电子政务建设情况并剖析福冈市案例。位于苏州工业园区的国信方舟软件技术有限公司(以下简称国信方舟),在过去的一年多时间里,一直参与日本地方电子政府的实施工程。本文将由他们介绍其亲身接触的日本电子政务。