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题名:
Cosa/Cosix系统Java虚拟机即时编译器的设计与实现
作者: 梅嘉
答辩日期: 2000
专业: 计算机软件与理论
授予单位: 中国科学院软件研究所
授予地点: 中国科学院软件研究所
学位: 博士
关键词: 虚拟机 ; 即时编译器
摘要: 随着数据网络的迅速发展,Java也逐渐被广泛使用在软件开发的各个领域。目前Java不仅仅是一种程序设计语言,而是一整套相关技术的集合。其中Java虚拟机(JVM)是Java的运行平台,是Java技术的核心。Java平台无关性的基础就是每个平台都配有自己的Java虚拟机。虚拟机屏蔽了不同软硬件平台之间的差异,它负责执行Java字节码文件。即时编译器(JIT)是虚拟机的一部分,它将Java字节码动态翻译成本地机器指令后再运行,能大大提高Java的运行速度。本论文的背景是开发基于国产开放系统平台Cosa/Cosix的Java虚拟机CoJava,主要的工作是为CoJava开发了即时编译器,并参与虚拟机主体的实现。在第一章前言之后,对虚拟机的设计和各关键技术进行了讨论,然后详细描述了CoJava即时编译器的设计与实现。每一个希望运行Java的平台都需要一个专门为它开发的虚拟机,如果它们被分别对待,其工作量无疑是巨大的。对于虚拟机主体来说,只要注意程序的可移植性,开发一个可以运行于各种平台的Java虚拟机是可能的,因为它只和操作系统打交道,而操作系统之间的差异可以用一些编程技巧来弥补。但是JIT的原理决定了它必定只能为运行于特定CPU上的特定操作系统开发。因为我们目前使用的Cosix1.3运行在Intel80386系列芯片上,所以我们的JIT也就是专为i386芯片开发的。但是在实现中,我们尽量考虑了今后向其它CPU移植的可能性,使用JIT部分经过不太大的修改就可以适应不同的CPU,做到了比较好的可移植性。当然在达到良好可移植性的同时,必然就损失了一些性能,这在与其它商业JVM的比较中可以看出来。但我们认为这些性能损失对于CoJava来说是值得的,因为运行速度不是追求的第一目标。
英文摘要: As the rapid spread of data networks, Java is more and more widely used in software development. Nowadays, Java couldn't be treated as only a kind of programming language, but a whole set of promising technologies. Java virtual machine(JVM), which is the running platform of Java, lies in the core of Java technologies. The basis of platform-independence of Java is that every platform has its own JVM. It is the JVM's responsibility to make the Java bytecode run as it's semantics, sheild the difference of operating systems and hardware platforms for upper Java program. Just-in-time compiler(JIT) is a part of JVM. It can translate Java bytecode to native machine code after loading which into memory and then let it run directly on CPU, thus greatly improve the performance of Java's execution. The background of this dissertation is the development of CoJava, a JVM base on the Chinese Operating System platform named Cosa/Cosix. the main job is to design and implement JIT for CoJava and to participate the implementation of CoJava JVM. In this paper, we discussed the design of JVM and critical technologies after the foreword, and depict the details of CoJava JIT. Every platform which is java-runnable must have its own JVM. If we developed JVM for each of them separately, we must end up with exhaustion. If we keep the portability of program intentionally when we develop the main body of JVM, it is possible to make out a JVM which could run on most platforms, because the main body of JVM only interact with OS and the differences between OS could be made up by programming skills. But the principle of JIT make it a truth that JIT must be developed for a given OS running on a given kind of CPU. Because Cosix which is our target platform running on Intel80386 chip, CoJava JIT is designed for it. Nevertheless, we make allowance for transplantation to other platform as possible as we can during the design and implementation of CoJava JIT. So the most part of JIT could be used to different platform without major changes. The portability of JIT is quite good. While we achieve the nice portability, we lost some performance as well, it is unavoidable. We could notice it while comparing with other commercial JVM. But we think it is worthwhile because the speed is not the most important goal, we could benefit much more from portability.
语种: 中文
内容类型: 学位论文
URI标识: http://ir.iscas.ac.cn/handle/311060/6866
Appears in Collections:中科院软件所

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Recommended Citation:
梅嘉. Cosa/Cosix系统Java虚拟机即时编译器的设计与实现[D]. 中国科学院软件研究所. 中国科学院软件研究所. 2000-01-01.
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