VB+ADO系统中数据库并发问题的检测和处理方法

在多用户数据库系统中,数据库并发问题已日益严重,并对系统造成严重危害.分析了数据库并发问题出现的情况,研究了在VB ADO系统中数据库并发问题出现的原因,以及检测和处理数据库并发操作和并发冲突的方法.     

ADO.NET中事务隔离级别的应用

在基于数据库的多用户应用中,事务并发错误是常见问题,采用事务隔离可以解决并发错误.在SQL Server 2005平台上模拟多事务并发场景,引发并发错误,给出使用ADO.NET的隔离级别控制事务并发的方法,提出事务和事物隔离级别的使用建议.     

数据库系统中动态调整串行次序的乐观并发控制算法

尽管已证明在RTDBSs中乐观并发控制方法的性能要优于锁式并发控制,但乐观并发控制存在不必要的重新启动以及较高的重启动代价的问题.该文介绍一种新的乐观并发控制算法,它通过结合动态调整串行次序和使用时标间隔来达到减少重新启动事务的目的,因而其性能高于传统的乐观并发控制方法.     

基于图文法的并发系统状态测试方法及其实现

在并发系统的研究和开发中，迫切需要一种能正确有效地描述并发系统的动态进程互联结构、动态进程通信和进程演化行为的形式化方法以及基于这种形式化方法的并发系统动态状态的测试手段．本文介绍一种基于图文法模型的并发系统状态测试方法，该方法与描述并发系统结构和行为的图文法模型相结合，构成了一个并发系统开发支持环境．这一方法可根据对并发系统的状态测试要求，在并发系统的运行期自动跟踪和记录并发系统的运行状态和通信情况，使并发系统的开发者可以实时地得到并发系统的运行状态，或者在并发系统运行结束后重演并发系统的状态变化过程.     

一种离散余弦变换电路的并发故障检测结构…

本文提出了一种离散余弦变换 (DCT)电路的并发故障检测结构。DCT采用 B.G.L ee算法蝶型结构实现 ,检测采用的方法是基于算法的并发故障检测容错方法。与其它并发故障检测容错结构相比 ,本文提出的并发故障检测 DCT结构在硬件及时间冗余度上均优越     

网络程序设计中的并发复杂性

互联网已成为现代社会的重要信息基础设施,然而网络环境的并发性使得传统程序设计方法在开发高质量的网络程序时遇到了许多困难,严重影响了开发效率.并发问题对网络程序开发复杂度的影响可以类比多核处理器带来的"软件并发危机",然而其中的并发问题却远远没有得到应有的重视.网络并发问题目前并不存在普适的应对方法,甚至在不同方法之间存...     

CSCW系统中的并发控制策略研究

并发控制是CSCW系统的关键技术之一,旨在解决由于多用户同时操作可能产生的冲突.本文首先分析了CSCW系统的并发控制问题产生的原因,然后简要介绍了CSCW系统中常用的并发控制方法,之后评述了几种典型的并发控制方法的改进策略,并在实例中应用操作转换方法和文档标注方法而对其进行了对比分析.     

离线并发冲突控制器的研究与实现

运用TCFG算法检测应用程序的离线并发冲突,提出了一种基于数据库离线并发冲突控制器的解决方案.首先对离线并发问题进行了认知与分解,在此基础上建立了总体设计模型.然后对该设计方案进行了分解,重点介绍了数据库离线并发冲突控制器的系统结构、关键技术及实现方法.实验结果表明,采用该方案能有效降低离线并发冲突的风险.     

典型数据并发访问问题的探讨

掌握好数据并发访问技术是保障数据库正确性、一致性所必需的.文章在实践的基础上总结出了并发事务设计原则,通过使用反复实验与测试的方法,对典型并发问题、自定义锁应用等作了深入探讨,进而得到了四种典型并发问题及两种典型并发应用的有效解决办法,为今后解决好各类数据库的并发访问问题起到积极的作用.     

多线程技术与分布式并发离散事件仿真

随着信息技术的快速发展和在实际的广泛应用,信息交换成本大幅降低,管理实践活动越来越呈现分布和并发特征.对于分布并发事件仿真因为仿真时钟同步问题,原有的离散事件仿真方法不能很好的进行模拟.多线程技术是并发事件仿真的有效方法,Net平台下多线程编程技术为这种实现提供便利,应用多线程技术能够实现对并发离散事件的仿真.最后针对一个分布式机械加工装配的例子用Visio建立起相应UML模型,并由此讨论该方法实现的可行性.     

并发行为对象的构造

本文提出了一种新的刻划并发行为的方法.这种方法的基础是笔者近年来设计并实现的一种面向对象的程序设计语言.尽管语言本身没有特别引入用于并发程序设计的设施,但它却能用来描述各种并发行为的模型,并以完善的高级形式提交给用户.     

RJ: a Java package providing JR‐like concurrent programming

The JR concurrent programming language extends Java with a richer concurrency model, by adding several new types and statements. JR provides dynamic remote virtual machine creation, dynamic remote object creation, remote method invocation, dynamic process creation, rendezvous, asynchronous message passing, semaphores, concurrent invocation, and shared variables. This paper presents RJ, a package for Java that provides JR‐like features. The paper gives an overview of RJ and its key features; describes the implications of RJ's design, including how RJ provides additional, useful flexibility; discusses the implementation of RJ; and gives qualitative and quantitative evaluations of our work with respect to feasibility and usability, experimentation, migration, and performance. RJ has been successful in meeting these goals and in providing insight into the trade‐offs between using a concurrent programming language versus using the equivalent concurrent package. Our work has yielded a few surprises in dealing with some concurrent programming language features, in understanding the run‐time performances of JR versus RJ programs, and in obtaining some additional, useful flexibility for concurrent programming applications. Copyright © 2015 John Wiley & Sons, Ltd.     

一个并发对象演算

由于缺乏一个为人们接受的描述并发对象系统语义的形式化模型,开发面向对象程序设计语言的开发受到了很大的制约,为了给并发面向对象程序设计定义一个公共的语义框架,人们分别以π演算和ａｃｔｏｒ模型为基础进行了研究。     

并发面向对象程序设计语言研究与进展

随着面向对象程序设计的普及和对并发应用程序需求的增加，并发面向对象程序设计语言的设计日益成为研究热点。     

Concurrent programming in VISO

Concurrent programming is more difficult to use and understand than sequential programming. In order to simplify this type of programming a number of approaches have been developed such as visual programming. Visual Occam (VISO) is a visual programming language for concurrent programming. It has a graphical syntax based on the language Occam and its semantics is represented both in petri net and process calculus. This paper presents a modular visual approach to write concurrent programs using the VISO language. Concurrent programs in VISO are specified graphically at different levels of abstraction. This paper describes this modular visual approach by constructing two examples in VISO. The first example is a simple concurrent program and it is mainly used to show the details of constructing a concurrent program in VISO. The second example is a larger concurrent program with more levels of abstraction. Copyright © 2000 John Wiley & Sons, Ltd.     

An implementation of the object-oriented concurrent programming language SINA

SINA is an object-oriented language for distributed and concurrent programming. The primary focus of this paper is on the object-oriented concurrent programming mechanisms of SINA and their implementation. This paper presents the SINA constructs for concurrent programming and inter-object communication, some illustrative examples and a message-based implementation model for SINA that we have used in our current implementation.     

Support for Implementation of Evolutionary Concurrent Systems

Concurrent programs that embed specifications of synchronizations in the body of their component are difficult to extend and modify. Small changes in a concurrent program, particularly changes in the interactions among components, may require re-implementation of a large number of components. Even specifications of components cannot be reused easily. This paper presents a concurrent program composition mechanism in which both specification and implementation of computations and interactions are completely separated. Separation of specifications and implementations facilitates extensions and modifications of programs by allowing one to separately change the implementations of computations and interactions. It also supports their reusability. The paper also describes the design and implementation of a concurrent object-oriented programming language based on this model, including a compiler for the language, and reports on the execution behavior of programs written in the language.     

Asynchronous communication model based on linear logic

We propose a new framework called ACL for concurrent computation based on linear logic. ACL is a kind oflinear logic programming framework, where its operational semantics is described in terms ofproof construction in linear logic. We also give a model-theoretic semantics based onphase semantics, a model of linear logic. Our framework well captures concurrent computation based on asynchronous communication. It will, therefore, provide us with a new insight into other models of asynchronous concurrent computation from alogical point of view. We also expect ACL to become a formal framework for analysis, synthesis and transformation of concurrent programs by the use of techniques for traditional logic programming. ACL's attractive features for concurrent programming paradigms are also discussed.