基于消息传递模型的众核拓扑重配置容错方法

系统故障恢复时间是众核系统容错的一项重要指标.为加快系统故障恢复,在基于消息传递模型的众核系统中提出一种快速的拓扑重配置容错方法.首先根据物理拓扑故障情况为每个核心定义映射区域,利用匈牙利算法快速构建初始解;然后通过限制交错映射的发生,采用禁忌搜索在初始解的基础上快速优化,获得最终重配置映射解;最后根据重配置映射解更新各运算节点上的节点映射关系表完成拓扑重配置,实现众核系统的核级容错.实验结果表明,该方法能够快速找到优化的拓扑重配置方案并成功地完成系统恢复,具有较低的容错时间开销.     

并发程序切片原型系统的设计与实现

并发程序切片是并发程序分析的一种重要手段。针对多线程共享变量通信机制,在通过程序分析工具CodeSurfer获取程序基本信息的基础上构造程序可达图,生成以程序状态和语句二元组为节点的并发程序依赖图,实现了基于程序可达图的并发程序切片原型系统。初步实验结果表明,与传统的切片方法相比,采用基于程序可达图的并发程序切片方法,可有效地解决依赖关系不可传递问题,获得高精度的并发程序切片。     

Parallel Wavefront Algorithms Solving Lyapunov Equations for the Cholesky Factor on Message Passing Multiprocessors

In this paper new parallel algorithms to solve the Lyapunov equations for the Cholesky factor using Hammarling's method on message passing multiprocessors are described. These algorithms are based on previous work carried out on the parallel solution of triangular linear systems by using row block data distribution and a wavefront of antidiagonals. The algorithms are theoretically analyzed and experimental results obtained on an SGI Power Challenge and a Cray T3D are presented.     

QNX消息传递及其在线程间通信的应用

本文介绍了QNX嵌入式实时多任务操作系统的消息传递和微内核体系结构的特点．创建线程的方法，消息传递的基本原理．以及阻塞式消息传递在线程间通信的实现方法．并给出了实例代码。     

程序切片技术在并发程序模型检查中的应用

模型检查技术在硬件和协议设计方面已经取得很大成功,但在软件验证方面仍存在很多困难。其主要问题是如何从源代码中自动抽取验证所要模型并精简其状态空间。文中通过对程序切片技术的研究,来解决并发程序验证的建模问题,包括把验证公式映射到切片准则．并把得到的程序切片转化为验证所需的模型。经程序切片处理后,软件模型检查效率得到提高。     

基于谓词动态切片技术的AOP测试用例生成方法研究

面向方面程序设计是面向对象程序设计技术的补充和完善,高效的面向方面程序测试方法是面向方面程序的质量保证.提出一个基于谓词动态切片技术的测试方法.首先,构造完整的AOP语句控制流图,它包含AOP的方面、切入点、连接点、建议等因素.然后,根据完整的AOP语句控制流图生成所有路径,针对每条路径,构造其分支函数,计算得到相应的测试数据,若路径不可执行,则不再计算其测试数据.在这个过程中,通过构建简化动态依赖图来生成谓词动态切片,再用谓词动态切片来帮助调整测试数据.最后,将各路径的实际输出数据与期望输出数据相比较,即可判断该程序是否有错误.经实例分析和实验验证,此方法可以系统地测试一个完整的面向方面程序,提高了测试数据的生成效率,并产生有效的测试用例.     

位置透明的MA可靠消息传递机制

移动Agent系统中的通信机制多由RMI加上消息发送机制实现,在现有的三种主流消息发送机制上进行改进,提出了新的消息转发策略——资源分散模型(Resource Distributed Model)。RDM提供了一种类似于结合了Homeagent和按路径转发方式的寻址策略,达到消息可达的目的,基于RDM的移动服务(Mobile Service)是一种在快速寻址后将消息快速转发的方式,MS减少了消息缓存部件的消息缓存量,并可用多个MS同时寻址从而提高消息发送速度。     

Heterogeneous Message Passing and a Link to Resource Management

Parallel process communication and system resource management have been seen as two separate entities in parallel and distributed systems. This causes difficulties in the dynamic mapping of newly spawned processes, because the application has little or no information on the availability, the connectivity and the current work-load of the target system. As a consequence, process mappings are often sub-optimal, overloading resources on one system while other processors are idling. We present a software system named "PLUS" that provides interprocess communication between different message passing models such as MPI, PVM and PARIX, and access to resource management systems for optimal process mapping and task migration.PLUS is a light-weight, extensible and efficient communication interface. With only four commands, PLUS is almost transparent ot the application code. Our current implementation supports inter-process communication between PVM, MPI and PARIX, but it can be easily extended to other vendor-specific message passing libraries. As PLUS has been designed for wide area networks, much effort has been spent on portability and on optimizing the communication speed across internet and also intranet links.     

一种基于时隙的邮件消息发布算法

移动计算环境与固定网络计算环境之间的巨大差异使建立专门的移动查询模型成为必要。该文简单介绍了笔者在工作中提出的一种基于“代理/邮箱”机制的移动查询模型,并以省电的查询过程为研究目标,提出了邮箱机制的核心算法———基于固定时隙分配的邮件消息投递算法,用户在每个消息发布周期内,只需对分配给自己的时隙进行监听,其余时间可以进入睡眠状态,从而达到节省电能的目的。通过对算法的分析和模拟结果表明:第一,与传统的查询过程相比,该算法能够大幅度地降低用户查询过程中处于工作状态时间占全部查询响应时间的比例,从而有效地支持了查询的省电性;第二,算法是以一定的延迟增加为代价来换取省电方面的收益,所以更加适用于大量的对查询实时性要求较低的移动查询应用。     

一种基于模块单子语义的动态程序切片方法

提出一种基于程序模块单子语义的新动态切片方法--模块单子动态切片.首先通过单子转换器,将切片这一类计算抽象成独立于具体语言的实体：切片单子转换器.然后,将该切片转换器作为模块加载到实际程序中,并给出相应的模块单子动态切片算法.据此,可直接在抽象语法结构上计算动态切片,不必记录程序执行历史;相应单子切片器也无需显式地构造诸如依赖图的中间结构.这种模块化抽象机制使得文中的动态切片算法具有很强的可扩展性和重用性.     

Web Application Slicing in Presence of Dynamic Code Generation

The computation of program slices on Web applications may be useful during debugging, when the amount of code to be inspected can be reduced, and during understanding, since the search for a given functionality can be better focused. The system dependence graph is an appropriate data structure for slice computation, in that it explicitly represents all dependences that have to be taken into account in slice determination.Construction of the system dependence graph for Web applications is complicated by the presence of dynamically generated code. In fact, a Web application builds the HTML code to be transmitted to the browser at run time. Knowledge of such code is essential for slicing. In this paper an algorithm for the static approximation of the dynamically generated HTML code is proposed. The concatenations of constant strings and variables are propagated according to special purpose flow equations, allowing the estimation of the generated code and the refinement of the system dependence graph.     

基于消息传递的时域分解并行算法研究

将Parareal算法中的预估校正格式加以改进,提出时域分解并行算法。基于主从模式和消息传递,具体考察了群体通信和非阻塞通信模式,并设计出通用而简便的并行化模型。在集群系统下对热传导方程和对流扩散方程的数值模拟结果表明:算法具有较高的加速性能以及良好的可扩展性,体现了时域分解的独特优势。     

并发程序的切片模型检验方法

提出了一种对并发程序进行切片以缩减模型检验状态空间的方法,首先针对并发程序中的同步与通信定义了一组依赖关系,包括并发分支与接合．非确定性,信道,共享变量等特征,对于从要验证的时态逻辑性质中提取的关于多个程序点的切片标准,文中给出算法根据相应的依赖关系通过不动点运算得到并发程序切片,可以证明得到的切片与原程序对于该性质具有相同的可满足性。     

一种面向对象程序的过程间切片算法

程序切片是一种程序分析技术，它通过把程序减少到只包含与某个特定计算相关的那些语句来分析程序，过程间切片作为图形可达性问题时，需要扩展过程内切片所用的程序依赖图（PDG）成系统依赖图（SDG），然后利用两阶段图形可达性算法计算比较精确的切片，目前程序切片技术的研究以面向对象程序切片为主，文中讨论了一种合适面向对象程序的分层切片方法，并综合分层切片方法和两阶段图形可达性算法提出了一种简化的计算面向对象程序过程间切片的算法。     

实时消息传递界面

实时系统消息传递界面(MPI/RT)是高性能计算中消息传递界面(MPI)在实时方面的扩展，可支持实时通信和实时系统的开发。文中介绍了MPI/RT的背景、开发的基本原理、重要技术和重要概念。描述了MPI/RT如何对双边、单边、零边3种类型的通信和时间驱动、事件驱动、优先级驱动3种实时典范以及这些典范的组合的支持。讨论了MPI/RT如何描述和满足高性能的实时系统的QoS要求。最后给出了一个用MPI/RT开发高性能的实时系统的一般过程。     

Shared Memory vs. Message Passing: The COMOPS Benchmark Experiment

This paper presents the comparison of the COMOPS benchmark performance in MPI and shared memory on four different shared memory platforms: the DEC AlphaServer 8400/300, the SGI Power Challenge, the SGI Origin2000, and the HP-Convex Exemplar SPP1600. The paper also qualitatively analyzes the obtained performance data based on an understanding of the corresponding architecture and the MPI implementations. Some conclusions are made for the inter-processor communication performance on these four shared memory platforms.     

A formal semantics for debugging synchronous message passing-based concurrent programs

In this paper, we propose a semantic framework to debug synchronous message passing-based con- current programs, which are increasingly useful as parallel computing and distributed systems become more and more pervasive. We first design a concurrent programming language model to uniformly represent exist- ing concurrent programming languages. Compared to sequential programming languages, this model contains communication statements, i.e., sending and receiving statements, and a concurrent structure to represent com- munication and concurrency. We then propose a debugging process consisting of a tracing and a locating procedure. The tracing procedure re-executes a program with a failed test case and uses specially designed data structures to collect useful execution information for locating bugs. We provide for the tracing procedure a struc- tural operational semantics to represent synchronous communication and concurrency. The locating procedure backward locates the ill-designed statement by using information obtained in the tracing procedure, generates a fix equation, and tries to fix the bug by solving the fix equation. We also propose a structural operational semantics for the locating procedure. We supply two examples to test our proposed operational semantics.     

Static and Dynamic Slicing of Constraint Logic Programs

Slicing is a program analysis technique originally developed for imperative languages. It facilitates understanding of data flow and debugging.This paper discusses slicing of Constraint Logic Programs. Constraint Logic Programming (CLP) is an emerging software technology with a growing number of applications. Data flow in constraint programs is not explicit, and for this reason the concepts of slice and the slicing techniques of imperative languages are not directly applicable.This paper formulates declarative notions of slice suitable for CLP. They provide a basis for defining slicing techniques (both dynamic and static) based on variable sharing. The techniques are further extended by using groundness information.A prototype dynamic slicer of CLP programs implementing the presented ideas is briefly described together with the results of some slicing experiments.     

面向消息中间件的设计与实现

首先简要介绍了商务质量消息的基本概念,然后着重对面向消息中间件设计思想和实现方法进行了阐述,并给出了它在中国国家现代化支付系统中的一个应用实例。     

含指针程序的单子切片方法

传统的含指针程序切片方法将指向分析与切片计算分开,增加了一定系统开销,为此文中提出一种可同时进行切片计算和指向分析的单子切片算法.该算法将程序正向切片思想与数据流迭代分析相结合,它是流敏感的,具有一定的精度,而且因指向分析和切片计算同时进行,故不需要像一般的流敏感分析方法那样记录每一个程序点的指向信息,而只需记录当前所分析的程序点处指向信息,从而节省了存储空间.此外,它还继承了原有单子切片方法所具有的强语言适应性和组合性.