一种提高Web服务性能的方法

首先阐述了Web服务器性能的定义，然后从Web服务器性能的几个关键问题入手，从应用负载，服务器软件和服务器硬件3个层面上详细讨论了如何解决这些关键问题，通过对比目前流行的测试工具，选择了合适的应用负载，采用探索式方法优化服务器软件的配置参数，从而减少了测试次数，通过屏蔽各种HTTP请求找出影响性能的瓶颈－对动态请求CAD GET的处理，针对该种请求，调整其在动态请求中所占的比例分析其对不同大小的文件在响应速度上的影响，最后优化相应的代码，将这一方案应用到曙光3000超级服务器上并使用SPECweb99作为Benchmark测出实验数据，对比改进前的结果，可以明显看到Web服务器的性能提高了一倍。     

WebFORCE MediaBase获得1997年网络计算最佳联接奖

ＷｅｂＦＯＲＣＥＭｅｄｉａＢａｓｅ获得１９９７年网络计算最佳联接奖日前，ＳＧＩ的ＷｅｂＦＯＲＣＥＭｅｄｉａＢａｓｅ媒体服务器软件在美国拉斯维加斯举办的“ＮｅｔＷｏｒｌｄ＋Ｉｎｔｅｒｏｐ”上荣获了最佳视频服务器奖项中的网络计算最佳联接奖，从而巩固了其在...     

SGI的对称多处理Web服务器系列

ＳＧＩ的对称多处理Ｗｅｂ服务器系列在Ｉｎｔｅｒｎｅｔ上的ＷＷＷ服务正在发生深刻的变化——从静态的，以文本为主的环境转向动态的，高度交互的环境。ＳＧＩ的Ｗｅｂ服务器系列ＷｅｄＦＯＲＣＥＣＨＡＬＬＥＮＧＥＤＭ、Ｌ、ＸＬ，由于采用了先进的ＣＨＡＬＬＥＮＧＥ...     

Web服务器与数据库的互连

１Ｗｅｂ服务器Ｗｅｂ主要有两大组成部分：Ｗｅｂ服务器和ｗｅｂ客户机,通常Ｗｅｂ服务器接收浏览器端的用户请求,服务器作出响应,形成ＨＴＭＬ文件后,把它发送给浏览器并中断链接。浏览器端则显示下载的ＨＴＭＬ文件。其关系如图１所示。１．１ＨＴＴＰ请求一个ＨＴＴＰ请求是从客户机发往服务器的,一般格式为：ＭｅｔｈｏｄＵＲＬ＿Ａｂｓｏｌｕｔｅ＿ＰａｔｈＰｒｏｔｏｃｏｌＶｅｒｓｉｏｎＮＬ［Ｈｅａｄ］［ＮＬＤａｔａ］Ｍｅｔｈｏｄ指明了发送到服务器的请求的类型,通常有三种：ＧＥＴ、ＰＯＳＴ和ＨＥＡＤＥＲ。ＵＲ＿Ｍｂ…     

SPECweb99：最晰Web服务器性能基准测试

１９９９年８月ＳＰＥＣ发布了最新Ｗｅｂ服务器性能基准测试ＳＰＥＣｗｅｂ９９,从而为信息系统建设中Ｗｅｂ服务器设备选型提供了有力的参考工具。简要介绍了ＳＰＥＣＷｅｂ９９,与ＳＰＥＣｗｅｂ９６作了比较,并指出了它存在的一些不足。     

基于Nginx负载均衡的动态改进算法

随着过去几十年互联网服务的指数增长,各大网站的访问量急剧上升。海量的用户请求使得热门网站的网络请求率可能在几秒钟内大规模增加。一旦服务器承受不住这样的高并发请求,由此带来的网络拥塞和延迟会极大地影响用户体验。负载均衡是高可用网络基础架构的关键组件,通过在后端引入一个负载均衡器,将工作负载分布到多个服务器来缓解海量并发请求对服务器造成的巨大压力,提高后端服务器和数据库的性能以及可靠性。而Nginx作为一款高性能的HTTP和反向代理服务器,正越来越多地应用到实践中。文中将分析Nginx服务器负载均衡的体系架构,研究默认的加权轮询算法,并提出一种改进后的动态负载均衡算法,实时收集负载信息,重新计算并分配权值。通过实验测试,对比不同算法下的负载均衡性能,改进后的算法能有效提高服务器集群的性能。     

一种动态负载均衡中间件的研究与实现

服务器集群可显著提高整个分布式系统的总体性能。本文针对用户请求服务时间变化大的特性,设计了一个跨平台、跨系统的动态负载均衡中间件工作模型,并对其中的关键问题给予详细描述。模型根据各服务器动态返回的负载信息并结合各服务器的性能进行动态负载调度,并以标准服务接口实现与分布式系统的无缝集成。性能测试表明该模型有效解决了集群的负载均衡问题。     

基于AHP的Web集群系统负载均衡算法

利用集群技术构建的服务器组在资源利用率上存在较大差异。为此,提出基于层次分析法(AHP)的集群系统负载均衡算法,建立判断矩阵,得到各项评估指标的单项和综合权重。调度器定时接收真实服务器上的4类参数：网络性能,服务器硬件,服务器软件和网络服务类型。根据调度器收到的每一个连接请求,采用动态反馈算法选择负载最小的服务器响应连接请求。实验结果表明,该算法能减少服务器平均响应时间,有效提高集群系统的响应率。     

Web服务器性能优化

该文论述ＨＴＴＰ协议的主要特性,分析了ＴＣＰ和ＨＴＴＰ的传输过程,阐述了ＨＴＴＰ与ＴＣＰ影响Ｗｅｂ服务器性能的原因,分析了各种网络特性对Ｗｅｂ服务器性能的影响和影响Ｗｅｂ服务器性能的主要因素,最后提出了优化ＷＷＷ系统性能的主要方法。     

异构系统中的Web服务器软件框架研究

在服务器端加入GPU或MIC等协处理器可以提升性能。但是,传统Web服务器端软件不能充分发挥多核CPU+MIC协处理器异构硬件体系的性能。为解决该问题,针对该硬件体系提出了一种新的Web服务器软件框架。该软件框架基于分阶段事件驱动模型,将部分动态请求调度至MIC协处理器执行,并可在多核CPU和MIC协处理器上并行处理动态请求。同时,通过采用自适应调度算法兼顾了CPU和MIC协处理器间的负载均衡。仿真实验表明,该模型在平均响应时间、吞吐量等方面均优于传统的基于先到先服务(First Come First Served,FCFS)的Web服务器软件模型。     

Web服务器性能评测

Web服务器性能评测是一种理解Web服务器对不同负载反应能力的方法，它对Web服务器的容量规划和性能增强有很大的帮助。讨论了Web服务器性能评测的原理、方法、难点及解决方案，介绍了基于Web负载的特点、ON／OFF源模型及浏览器／服务器体系结构，开发了一个Web服务器性能评测工具－WSBench。WSBench产生渐近自相似的HTTP请求序列，从静态文档、动态文档（没有数据库存取）、动态文档（有数据库存取）及前三者根据Zipf法则的组合4个层次来评测Web服务器的性能。性能测试结果表现为每秒请求数、每秒字节数和往返时间3个指标。最后讨论了Web服务器性能问题及使用WSBench测得的指标来建议Web服务器性能增强可以采用的方法。     

Optimizing utilization of resource pools in web application servers

Among the web application server resources, the most critical for their performance are those that are held exclusively by a service request for the duration of its execution (or some significant part of it). Such exclusively held server resources become performance bottleneck points, with failures to obtain such a resource constituting a major portion of request rejections under server overload conditions. In this paper, we propose a methodology that computes the optimal pool sizes for two such critical resources: web server threads and database connections. Our methodology uses information about incoming request flow and about fine‐grained server resource utilization by service requests of different types, obtained through offline and online request profiling. In our methodology, we advocate (and show its benefits) the use of a database connection pooling mechanism that caches database connections for the duration of a service request execution (so‐called request‐wide database connection caching). We evaluate our methodology by testing it on the TPC‐W web application. Our method is able to accurately compute the optimal number of server threads and database connections, and the value of sustainable request throughput computed by the method always lies within a 5% margin of the actual value determined experimentally. Copyright © 2010 John Wiley & Sons, Ltd.     

HGS:一种新的Web服务器负载生成策略

在Web服务器性能评测研究中 ,服务器负载的特性分析是一个非常重要的研究内容。准确地把握服务器负载的统计规律 ,建立负载模型是服务器性能仿真的基础。该文在详细分析Web服务器负载特性的基础上 ,建立了一个新的服务器负载层次结构模型 ,设计的层次生成策略HGS(HierarchicalGenerationStrategy)符合客户请求的基本特性 ,适用于各种Web服务器性能研究。     

Characterization and Evaluation of Cache Hierarchies for Web Servers

As Internet usage continues to expand rapidly, careful attention needs to be paid to the design of Internet servers for achieving high performance and end-user satisfaction. Currently, the memory system continues to remain a significant performance bottleneck for Internet servers employing multi-GHz processors. In this paper, our aim is two-fold: (1) to characterize the cache/memory performance of web server workloads and (2) to propose and evaluate cache design alternatives for future web servers. We chose SPECweb99 as the representative web server workload and our entire characterization and evaluation methodology is based on our CASPER simulation framework. We begin by exploring the processor cache design space for single and dual-processor servers. Based on our observations, we then evaluate other cache hierarchy alternatives such as chipset caches, coherence filters and decompressed page stores. We show the sensitivity of these components to basic organization parameters such as cache size, line size and degree of associativity. We also present the performance implications of routing memory requests initiated by I/O devices through these caches. Based on detailed simulation data and its implications on system level performance, this paper shows that chipset caches have significant potential for improving future web server performance.     

DPSP:一种基于内容的客户请求调度策略

改善执行服务器的性能对于提高Web服务器的服务质量至关重要，在分析执行服务器的线程数量，调度策略，服务器响应时间和客户请求到达率间相互关系的基础上，提出了动态优先级调策略DPSP（dynamic priority scheduling policy)，它根据客户请求内容的重要程序有效地组织服务器的请求执行顺序，达到提高请求服务质量的目的，与先来先服务FCFS（first come first service)，短请求优先SRF（short request first)和DEDF（dynamic earliest deadline first)策略进行模拟比较表明，DPSP策略以较小的响应延迟增量为代价，提高了WWW的服务质量。     

一种基于客户地址的QoS Web服务器的设计与实现

设计并实现了一种基于客户地址的ＱｏＳ Ｗｅｂ服务器,它能对客户的服务请求设定不同的服务等级,并按不同的服务策略响应客户的服务请求。实验结果表明,ＱｏＳ Ｗｅｂ服务器能够有效地实现了期望的ＱｏＳ服务。     

Managing database server performance to meet QoS requirements in electronic commerce systems

The performance of electronic commerce systems has a major impact on their acceptability to users. Different users also demand different levels of performance from the system, that is, they will have different Quality of Service (QoS) requirements. Electronic commerce systems are the integration of several different types of servers and each server must contribute to meeting the QoS demands of the users. In this paper we focus on the role, and the performance, of a database server within an electronic commerce system. We examine the characteristics of the workload placed on a database server by an electronic commerce system and suggest a range of QoS requirements for the database server based on this analysis of the workload. We argue that a database server must be able to dynamically reallocate its resources in order to meet the QoS requirements of different transactions as the workload changes. We describe Quartermaster, which is a system to support dynamic goal-oriented resource management in database management systems, and discuss how it can be used to help meet the QoS requirements of the electronic commerce database server. We provide an example of the use of Quartermaster that illustrates how the dynamic reallocation of memory resources can be used to meet the QoS requirements of a set of transactions similar to transactions found in an electronic commerce workload. We briefly describe the memory reallocation algorithms used by Quartermaster and present experiments to show the impact of the reallocations on the performance of the transactions. Published online: 22 August 2001     

一种基于Web Service的分级QoS的研究与实现

随着Web Service技术的广泛应用,Qos成为一个非常重要的问题．以服务响应时间为Qos参数,验证了一种基于Web Service的分级QoS方法,提出了目标时间预设模型,并针对优化问题提出一种基于动态规划的解决方法,并实现了原型系统．实验数据表明这种方法有效地控制了负载平衡,实现了服务分级．     

An approximation-based load-balancing algorithm with admission control for cluster web servers with dynamic workloads

The growth of web-based applications in business and e-commerce is building up demands for high performance web servers for better throughputs and lower user-perceived latency. These demands are leading to a widespread substitution of powerful single servers by robust newcomers, cluster web servers, in many enterprise companies. In this respect the load-balancing algorithms play an important role in boosting the performance of cluster servers. The previous load-balancing algorithms which were designed for the handling of static contents in web services suffer from significant performance degradation under dynamic and database-driven workloads. Regarding this, we propose an approximation-based load-balancing algorithm with admission control for cluster-based web servers in this study. Since it is difficult to accurately determine the loads of web servers through feedbacks from distributed agents in web servers, we propose an analytical model of a web server to estimate the web servers’ loads. To achieve this, the algorithm classifies requests based on their service times and track numbers of outstanding requests for each class of each web server node and also based on their resource demands to dynamically estimate the loads of each node. For the error handling of the model a proportional integral (PI) controller from control theory is used. Then the estimated available capacity of each web server is used for load balancing and admission control decisions. The implementation results with a standard benchmark confirm the effectiveness of the proposed scheme, which improves both the mean response time and the throughput of the cluster compared to rival load-balancing algorithms, and also avoids situations in which the cluster is overloaded, even when the request rates are beyond the cluster capacity.