Web服务器集群系统具有优良的可扩展能力、高性能和高可用性,并且可以由低端设备来搭建,性能价格比高。正是凭借独特的技术优势,Web服务器集群在这几年迅速发展,其应用得到不断的推广。但是Web服务器集群的某些性能还不尽如人意,负载均衡算法是提升其性能的关键。
本文在研究了Web服务器集群相关技术并分析了当前主流负载均衡算法的优点与不足基础上,提出了一种新的基于请求量化和分类的动态负载均衡算法,LBRQC (Load Balancing based on Requests Quantification and Classification)。算法引入了请求开销量化、请求分类机制,并通过请求就绪进程队列的类别和长度来描述服务器负载状态的方法,降低了调度器获取服务器负载信息的复杂度和系统资源开销,同时有效地提高了服务器负载信息的精确度,从而实现有效的负载均衡；算法还引入了准入控制避免了系统过载而使其保持较高的性能水平。我们使用了随机Petri网模型方法为该算法的Web服务器集群系统建立了高级随机Petri网模型(SHLPN),最后使用随机Petri网软件包(SPNP)对该模型进行的仿真实验结果表明,与动态WRR算法和CAP算法相比本文算法具有较高吞吐率和较低响应延迟性能。
The study on the static and dynamic load balancing algorithms has a history over three decades and it is stilla promising field. But because of the uncertainties between the dependencies of the parallel tasks and thei...
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The study on the static and dynamic load balancing algorithms has a history over three decades and it is stilla promising field. But because of the uncertainties between the dependencies of the parallel tasks and their communi-cation during the compile-time, researchers are more inclined to study the dynamic load balancing algorithms(DLB).There are almost four kinds of DLB algorithms including the centralized DLB, distributed DLB, global DLB and LocalDLB, all of them have their pros and cons. This paper addresses a new dynamic load balancing model based on theMain Load Information Table (MLIT) and its dynamic load balancing algorithm, it not only has the advantages thefour models above mentioned have, but it overcomes some of their disadvantages which lead to a poor performance,thus it boasts a better stability and security and in the end it can improve the performance of the system.
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