【作者】 邹方曼；

【导师】 高泽华；

【作者基本信息】 北京邮电大学 ， 电子与通信工程（专业学位）， 2013， 硕士

【摘要】 随着信息化进程的推进,分布式系统得到了广泛的应用和重视,但是由于任务到达的随机性,分布式系统中经常出现不同机器负载差异过大的现象。为解决这个问题,提出了负载均衡技术。负载均衡技术能合理的将客户端的请求分配到系统节点中,使得各个服务器的负载大致相同,从而能快速响应客户端的请求,提高整个系统的性能。本文前三章描述了研究课题的背景和意义,介绍了负载均衡的基本概念并分析了分布式系统中负载均衡实现的方式。在此基础上,提出了一种适用于集中式(即中间节点负责调度任务)分布式系统的动态负载均衡框架。该框架通过SNMP协议远程获取标识服务器负载信息的参数,并通过一种改进的动态负载均衡策略调度任务。它能够有效的选取当前最佳的服务器(通常是空闲和低负载服务器)响应客户端的请求,实现任务的均衡分配。使用中,不需要安装其他的程序,只需将此框架嵌入到分布式系统中间件中即可实现系统的负载均衡。本文提出的系统全部使用Java语言实现。得益于Java语言的平台无关性,该框架具有一定的通用性,能运行于不同类型的平台上。然而,由于Java运行的效率相对较低,而且本课题以集中式系统为模型开发,使得该框架在大型复杂系统中具有一定的局限性,主要应用在中小企业的负载均衡中。本文的最后,搭建环境测试系统框架的可用性,并通过对结果的分析,证明了该框架的可行性,顺利完成了课题的任务。更多还原

【Abstract】 With the development of information process, the distributed system has been widely applied and highly valued. However, as the processes arrive randomly, different servers in the distributed system may have considerably defferent load. To solve this problem, the load balancing technology has been proposed. Load balancing can reasonably assign the requests of the client to different servers, which can make each server has roughly the same load. In this way, the system can respond the request quickly and the entire performance of the system improves.The first three chapters in this paper describe the background and significance of the research topic, introduce the basic concepts of load balancing and analyze the methods to achieve load balancing in distributed systems. On the basis of these knowledge, a dynamic load balancing framework for centralized (ie, an intermediate node responsible for scheduling tasks) distributed system is proposed. The framework gets parameters that can identify the server’s load information remotely through the SNMP protocol, and it improves a dynamic load balancing strategy. It can effectively select the best server (usually idle or low load server) to respond the client’s request and distribute the processes to the servers evenly. In practice, embeding this framework in distributed system’s middleware simply can achieve the load balancing without installing other programs.The framework proposed in this paper achieved totally via Java language. As Java is independent on the platforms, the framework can commonly be used on different types of programs. However, due to the low efficiency of Java and the bottlenecks role of the intermediate node, the framework has certain limitations in large and complex systems but can be well applied to SMES’s load balancing systems.In the end of the paper, we built a test environment to prove the feasibility of the framework. Through the analysis of the results proved the feasibility of the framework and the successful completion of the task.更多还原