基于嵌入式Java虚拟机的垃圾收集优化算法

对分代垃圾收集算法进行分析和改进,提出一种适用于嵌入式Java虚拟机的垃圾收集优化算法。采取动态的分代方式,将旧生代的回收工作细分,从而充分利用堆空间,缩短分代回收中全收集导致的停顿时间。实验结果表明,该算法能保持较高的垃圾收集效率,系统平均停顿时间较少。     

Java虚拟机中异常机制实时性的研究及实现

异常处理机制是程序设计语言的重要特征之一。讨论了对Java异常处理进行实时性改造的可行性和具体方法,并且在Linux平台上,实现了对开源Java虚拟机SableVM中异常处理机制的实时性改造。实验结果表明改进后的虚拟机在异常捕获时间趋于线性的同时,异常表查询效率也得到了提高。     

基于内核态JVM的Linux设备驱动程序

驱动程序的不稳定是造成操作系统内核崩溃的主要原因,该文采用类型安全的Java语言开发Linux设备驱动程序以提高系统的稳定性,并分析驱动模型的结构、内核态Java虚拟机(JVM)的设计以及Java驱动程序的编写。USB网卡的测试验证了Java驱动在提高系统稳定性上的优势。     

Java虚拟机的剖析

深入理解Ｊａｖａ虚拟机的组成部分及内部是怎样运行的，并以例子说明虚拟机中相关的字节码与内部运行过程。     

Java虚拟机中Java栈以及相关指令的实现

Java栈是Java虚拟机中运行时数据区的主要组成部分。大部分虚拟机指令的操作都与Java栈中的框架相关联。该文描述了Java栈在Java虚拟机运行中所起的作用,自行设计了一种Java栈的数据结构,提出了一些具有代表性的字节码指令的实现方法。同时总结了Java栈对虚拟机运行效率的影响。     

Java虚拟机使用及优化

Java语言在中、大型应用中,其使用、优化仍然是系统成熟的必经之路。然而如何更好的使用以及优化Java虚拟机,使其发挥更好的作用,却需要经过各个方面的分析、改进。文章介绍了JDK6以下的虚拟机的特性,并指出了一种通用的优化方法,为各种基于Java的产品的开发、发布提供参考。     

.NET中通用语言运行时环境初探

2000年微软公司推出了．NET构架，向网络计算和分布式跨平台计算迈出了鼓舞人心的一步，通过对JVM和CLR及作对比，着重介绍了．NET跨平台计算的核心设施和跨平台计算的实现思想。     

Java环境下内存受限系统的研究

在Java应用的开发中内存受限的处理是一个技术难点。根据网络应用系统的特点,分析了Java系统的内存管理和运行机制,提出了一种通过减小类结构空间和生成对象空间的内存受限解决方案,并对其性能进行了分析和评测。     

实时性分布嵌入式系统设计

分布嵌入式系统的应用通常具有实时性要求,其实时性需要从任务调度、通信协议、调用接口和嵌入式操作系统四个方面得到支持。采用两阶段调度策略既可以保证调用的透明性,又可以简化任务调度算法;基于优先级的线路竞争算法可以改进以太网使其符合实时性要求;采用微型Java虚拟机作为分布式中间件可以为系统调用接口提供一个统一的支持平台。     

The design and implementation of a modular and extensible Java Virtual Machine

This paper describes the design, implementation, and experimental evaluation of a modular and extensible Java? Virtual Machine (JVM) infrastructure, called Jupiter. The infrastructure is intended to serve as a vehicle for our research on scalable JVM architectures for a cluster of PC workstations, with support for shared memory in software. Jupiter is constructed, using a building block architecture, out of many modules with small, simple interfaces. This flexible structure, similar to UNIX® shells that build complex command pipelines out of discrete programs, allows the rapid prototyping of our research ideas by confining changes in JVM design to a small number of modules. In spite of this flexibility, Jupiter delivers good performance. Experimental evaluation of the current implementation of Jupiter using the SPECjvm98 and the EPCC Java Grande single‐threaded and multithreaded benchmarks reflects competitive performance. Jupiter is on average about 2.5 times faster than Kaffe and about 2 times slower than the Sun Microsystems JDK (interpreter versions only). By providing a flexible JVM infrastructure that delivers competitive performance, we believe we have developed a framework that supports further research into JVM scalability. Copyright © 2003 John Wiley & Sons, Ltd.     

Compiling lazy functional programs to Java bytecode

The Java Virtual Machine (JVM) was designed as the target for Java compilers, but there is no reason why it cannot be used as the target for other languages. We describe the implementation of a compiler which translates a lazy, weakly‐typed functional program into Java class files. We compare the performance of our compiler to the only other known compiler from a lazy functional language to the JVM. The results are broadly similar, suggesting that to get a significant performance speed‐up using this compilation paradigm will come only from increasing the performance of the JVM, rather than enhancing the compiler itself. Copyright © 1999 John Wiley & Sons, Ltd.     

嵌入式Java反射机制的设计与实现

Java反射是提高软件系统灵活性的重要技术,它是Java被视为动态语言的一个关键特性。虽然CLDC规范并不支持反射,但是在基于Java技术的嵌入式领域,反射仍有其应用需求。Sun公司根据CLDC规范发布了一套嵌入式Java技术的参考实现,其虚拟机被称作KVM。通过分析KVM的相关数据结构和机制,详细描述了反射机制的设计原理,并提出了一种在KVM中扩展反射功能的实现方案,经过测试证明该方案是可行的。     

清剿Java程序中的内存泄漏

Java语言的一个显著特点是它通过虚拟机和垃圾回收机制管理着大部分的内存事务,但是在Java程序中还是可能存在内存泄漏问题。文中首先对Java内存泄漏做一个简要的定义,接着围绕一个实例详细地介绍如何用工具检测Java内存泄漏,最后列举了一些典型的泄漏,以便读者在Java程序开发中尽量避免类似的内存泄漏。     

A Type System for the Java Bytecode Language and Verifier

The Java Virtual Machine executes bytecode programs that may have been sent from other, possibly untrusted, locations on the network. Since the transmitted code may be written by a malicious party or corrupted during network transmission, the Java Virtual Machine contains a bytecode verifier to check the code for type errors before it is run. As illustrated by reported attacks on Java run-time systems, the verifier is essential for system security. However, no formal specification of the bytecode verifier exists in the Java Virtual Machine Specification published by Sun. In this paper, we develop such a specification in the form of a type system for a subset of the bytecode language. The subset includes classes, interfaces, constructors, methods, exceptions, and bytecode subroutines. We also present a type checking algorithm and prototype bytecode verifier implementation, and we conclude by discussing other applications of this work. For example, we show how to extend our formal system to check other program properties, such as the correct use of object locks. This revised version was published online in August 2006 with corrections to the Cover Date.     

嵌入式JAVA虚拟机的加速改造

首先分析了Sun公司的嵌入式Java虚拟机KVM性能低效的原因,在此基础上引入两种Java虚拟机性能加速技术:JIT和Native线程。通过建立MVM模型,将这两种加速技术融合到了Java虚拟机中,并详细介绍了实现这两种加速技术的关键数据结构和算法。实验结果表明Java虚拟机的性能获得明显的提高。     

A distributed implementation of a virtual machine for Java

The cluster virtual machine (VM) for Java provides a single system image of a traditional Java Virtual Machine (JVM) while executing in a distributed fashion on the nodes of a cluster. The cluster VM for Java virtualizes the cluster, supporting any pure Java application without requiring that application be tailored specifically for it. The aim of our cluster VM is to obtain improved scalability for a class of Java Server Applications by distributing the application's work among the cluster's computing resources. The implementation of the cluster VM for Java is based on a novel object model which distinguishes between an application's view of an object (e.g. every object is a unique data structure) and its implementation (e.g. objects may have consistent replications on different nodes). This enables us to exploit knowledge on the use of individual objects to improve performance (e.g. using object replications to increase locality of access to objects). We have already completed a prototype that runs pure Java applications on a cluster of NT workstations connected by a Myrinet fast switch. The prototype provides a single system image to applications, distributing the application's threads and objects over the cluster. We used the cluster VM to run, without change, a real Java Server Application containing over 10 Kloc

1 Kloc means Kilo lines of code—used to describe the size of applications in terms of source lines count.

for the source code and achieved high scalability for it on a cluster. We also achieved linear speedup for another application with a large number of independent threads. This paper discusses the architecture and implementation of the cluster VM. It focuses on achieving a single system image for a traditional JVM on a cluster while describing, in short, how we aim to obtain scalability. Copyright © 2001 John Wiley & Sons, Ltd.     

基于程序约束的细粒度JVM测试程序约简方法

为了对Java虚拟机(JVM)进行测试,开发人员通常需要手工设计或利用测试生成工具生成复杂的测试程序,从而检测JVM中潜在的缺陷。然而,复杂的测试程序给开发人员定位及修复缺陷带来了极高的成本。测试程序约简技术旨在保障测试程序缺陷检测能力的同时,尽可能的删减测试程序中与缺陷检测无关的代码。现有研究工作基于Delta调试在C程序和XML输入上可以取得较好的约简效果,但是在JVM测试场景中,具有复杂语法和语义依赖关系的Java测试程序约减仍存在粒度较粗、约简效果较差的问题,导致约简后的程序理解成本依然很高。因此,针对具有复杂程序依赖关系的Java测试程序,本文提出一种基于程序约束的细粒度测试程序约简方法JavaPruner。首先在语句块级别设计细粒度的代码度量方法,随后在Delta调试技术上引入语句块之间的依赖约束关系来对测试程序进行约简。以Java字节码测试程序为实验对象,通过从现有的针对JVM测试的测试程序生成工具中筛选出具有复杂依赖关系的50个测试程序作为基准数据集,并在这些数据集上验证JavaPruner的有效性。实验结果表明,JavaPruner可以有效删减Java字节码测试程序中的冗余代码。与现有方法相比,在所有基准数据集上约减能力平均可提升37.7%。同时,JavaPruner可以在保障程序有效性及缺陷检测能力的同时将Java字节码测试程序最大约简至其原有大小的1.09% ,有效降低了测试程序的分析和理解成本。     

Platform Independent Timing of Java Virtual Machine Bytecode Instructions

The accurate measurement of the execution time of Java bytecode is one factor that is important in order to estimate the total execution time of a Java application running on a Java Virtual Machine. In this paper we document the difficulties and solutions for the accurate timing of Java bytecode. We also identify trends across the execution times recorded for all imperative Java bytecodes. These trends would suggest that knowing the execution times of a small subset of the Java bytecode instructions would be sufficient to model the execution times of the remainder. We first review a statistical approach for achieving high precision timing results for Java bytecode using low precision timers and then present a more suitable technique using homogeneous bytecode sequences for recording such information. We finally compare instruction execution times acquired using this platform independent technique against execution times recorded using the read time stamp counter assembly instruction. In particular our results show the existence of a strong linear correlation between both techniques.     

嵌入式系统中Java虚拟机的研究与移植

研究了Java平台的核心——虚拟机（JVM）,主要分析了开放源码的Java虚拟机Kaffe的结构、运行机制,并针对特定的嵌入式应用,研究了将Kaffe移植到给定的处理器和操作系统之上的关键技术,给出了相应的移植方案,对Java虚拟机在嵌入式系统中的应用具有较大的指导意义。     

Java程序内存泄漏综述

从与C/C++内存泄漏对比的角度分析了Java内存泄漏问题,详细介绍了Java内存泄漏的相关研究和工具,探讨了当前研究和工具中存在的不足并分析了其原因,总结了内存泄漏相关领域研究的发展趋势。