基于优先级服务的排队系统模型的计算机模拟研究

基于TCP／IP协议的拥塞问题、Internet QoS分析都需考虑优先级服务的排队系统。讨论了服务规则为服从优先级服务的模拟模型,分别在串并联混合情形下建立四类模拟模型,最后给出模拟实例。     

一种基于多优先级队列和QoS的服务调度策略

针对网格服务流程的特点,在多维调度策略分析基础之上,提出基于多优先级队列和QoS的服务调度模型,并给出划分逻辑子网的思想,为具有不同需求的不同服务分配到最佳资源并得到最优处理.实验对资源调度公平性、服务请求响应时间等指标进行了测试,充分表明该调度模型的有效性.     

基于J2EE的银行客户信用评级系统研究与实现

为适应巴塞尔新协议金融环境的变化,银行客户信用评级系统基于J2EE技术体系结构从数据来源、客户评级、评级审批和安全管理等方面进行了设计研究.论文介绍了银行客户信用评级系统建设的背景,详细论述了应用客户/Web服务器/应用服务器/数据库服务器体系的系统主要功能和实现技术手段.     

中心队列二次门限服务的轮询系统分析

采用嵌入Markov链和概率母函数的方法对门限服务优先级排队系统进行分析,提出普通队列和高优先级队列分别采用基本门限和二级门限的服务机制,得出了平均排队队长和平均查询周期的解析式。     

基于优先队列的时变网络最短路径算法

提出了基于优先队列的时变网络最短路径算法,能克服传统最短路径算法难以对时变网络求解最短路径的缺陷。提出的时间窗选择策略能够在算法求解过程中为节点选择合适的时间窗以降低路径长度,从而求得精确解。进一步地,算法使用了优先队列组织节点集合以提高计算效率。在随机生成的网络数据以及美国道路数据上的实验表明,基于优先队列的时变网络最短路径算法与经典方法相比,不仅能够求得精确解,运算速度也有所提高。     

优先级队列的缓存管理机制的性能分析

为了解决好计算机网络中的多媒体通信以及对服务质量的要求,提出了一种基于优先级队列的缓存管理机制。详细研究了该机制的实现原理和方法,并给出了相关的性能分析,并建立端对端多媒体通信系统环境,进行了实验,证明了该缓存管理机制能很好地解决多媒体通信的拥塞控制,满足多媒体通信服务质量的要求。     

基于优先级队列的分布式多主题爬虫

在分布式环境中,为提高资源利用率和网页抓取效率,提出一种基于优先级队列的分布式多主题爬虫调度算法PQ‐MCSA。利用基于缓存的扩展式哈希算法对整体任务集进行切割,按照URL逻辑二级节点哈希映射法,将分割后的子任务集均匀地分配到各处理节点中;利用单处理节点的计算能力结合构建的任务优先级队列进行不同主题任务的调度。该算法改善了传统分布式爬虫对单节点的处理资源调度不充分、多主题任务爬取不均匀等缺点。实际项目的应用结果表明,使用该方法能够有效地提高各主题爬取结果的均衡度,具有较强的实用性。     

An application of program unification to priority queue vectorization

In this experimental study, we apply the technique of program unification to priority queues. We examine the performance of a variety of unified priority queue implementations on a Cray Y-MP. The scope of the study is restricted to determining if different implementations of priority queues exhibit markedly different performance characteristics under program unification. We found this to be true. In a larger view, this result has interesting consequences in the application of program unification to discrete event simulations on vector or SIMD machines. We find the heap to be a promising data structure in the program unification paradigm.This research was supported by the National Science Foundation under Grant No. ASC-9002225, and by NATO under Grant CRG 900108.Also supported in part by the Mathematical Sciences Section of Oak Ridge National Laboratory under contract DE-AC05-84OR21400 with Marietta Energy Systems, Inc.     

基于动态权值优先级队列的移动消息推送策略

针对传统的加权循环队列调度在移动消息推送平台中会增加系统开销、延长消息发送时间等问题,提出一种基于动态权值的加权循环调度策略.该策略在原有加权循环调度算法基础上,采用了动态权值策略,使得推送系统不再需要对消息的发送情况作额外的记录,有效降低了系统开销.对提出的算法进行了模拟实验,实验结果表明,改进的策略减少了消息发送的整体时延,提高了移动推送平台的消息发送效率.     

Parallel heap: An optimal parallel priority queue

We describe a new parallel data structure, namely parallel heap, for exclusive-read exclusive-write parallel random access machines. To our knowledge, it is the first such data structure to efficiently implement a truly parallel priority queue based on a heap structure. Employing p processors, the parallel heap allows deletions of (p) highest priority items and insertions of (p) new items, each in O(log n) time, where n is the size of the parallel heap. Furthermore, it can efficiently utilize processors in the range 1 through n.This work was supported by U.S. Army's PM-TRADE contract N61339-88-g-0002, Florida High Technology and Industry grant 11-28-716, and Georgia State University's internal research support during spring and summer quarters, 1991.     

Analysis of a nonpreemptive priority queue with SPP arrivals of high class

This paper considers a nonpreemptive priority queueing system with two priority classes of customers, where high priority customers arrive to the system in accordance with a switched Poisson process (SPP) and low priority customers in accordance with a Poisson process. Using the supplementary variable technique, we derive the joint probability generating function of the stationary queue length distributions and the Laplace-Stieltjes transforms of the stationary waiting time distributions of high and low priority customers. We also present some numerical results in order to show the computational feasibility of the analytical results.     

基于排队论的Web服务社区最优服务数设置

Web服务社区是将功能类似的Web服务集中到一起为用户提供服务,当大量用户同时访问社区时,会出现排队现象。用户在社区中排队时会占用一部分资源,从而会产生一部分额外的成本。为此研究了如何设置最优的服务数使得这部分的额外成本最小。给出Web服务社区的定义,将在服务社区中排队的问题映射成排队论问题,确定排队模型为M/M/n。计算在稳定状态时用户的排队长度,得出在社区中排队的用户数量。结合Web服务社区中的成本因素确定成本函数,结合经济学中的边际分析法求出最佳的服务数。实验表明：该方法可以有效地找出最优的服务数,且效率较高。     

Modelling priority queuing systems with varying service capacity

Many studies have been conducted to investigate the performance of priority queuing (PQ) systems with constant service capacity. However, due to the time-varying nature of wireless channels in wireless communication networks, the service capacity of queuing systemsmay vary over time. Therefore, it is necessary to investigate the performance of PQ systems in the presence of varying service capacity. In addition, self-similar traffic has been discovered to be a ubiquitous phenomenon in various communication networks, which poses great challenges to performance modelling of scheduling systems due to its fractal-like nature. Therefore, this paper develops a flow-decomposition based approach to performance modelling of PQ systems subject to self-similar traffic and varying service capacity. It specifically proposes an analytical model to investigate queue length distributions of individual traffic flows. The validity and accuracy of the model is demonstrated via extensive simulation experiments.