硬Java实时嵌入式平台及其关键技术研究
发布时间：2018-08-02 18:11
【摘要】：随着嵌入式计算及实时计算的迅速发展,嵌入式实时开发模式正在经历快速变革,与传统的采用汇编语言或者C/C++的开发模式相比,Java不仅在可移植性、高开发效率、低开发/维护成本等方面有自身的优势,而且能够提供更高层次的抽象水平,可以满足更高级别的数据建模需求,同时还具有强大的类库支持。Java的跨平台、面向对象、可靠性、语言级的并发支持、严格的类型检查、健壮、安全等特点,使其具备了作为嵌入式实时开发语言的基础,但是标准Java并非专门为实时应用设计,尚不能够完全满足实时系统开发的要求,还需要有针对性地进行Java的实时扩展和规范。随着实时Java社区的努力,以及Java实时规范(RTSJ)和安全关键Java(SCJ)的推出,扩展后的实时Java具备了作为嵌入式实时开发语言的资格,而且得到了一系列成功的应用。目前,针对实时Java及其支撑平台的研究逐渐成为热点,出现了一些支持实时Java的平台和虚拟机,这些平台和虚拟机大多以软件的形式实现。对于资源受限的嵌入式实时系统而言,软件Java平台和虚拟机由于通常存在着运行速度慢、执行效率低、资源开销大等问题,在发挥Java的性能优势方面仍然面临一定的困难。相对而言,采用Java处理器直接执行字节码,实现一种硬Java(hard Java)的引擎执行模式,可以在提高运行效率的同时,大幅度降低功耗与资源占有率,尤其适合资源受限环境的嵌入式实时Java应用。 本文设计并实现了一款能够支持实时Java的用于资源受限环境的硬Java实时嵌入式平台hJrep(hard Java real-time embedded platform),并对其中的关键技术进行了深入研究和探讨。hJrep以Java处理器为执行引擎,以Java字节码作为本地指令,实现了对字节码的硬件直接执行。本文的主要创新性工作包括： (1)为硬Java实时嵌入式平台提出了一种运行时可预测的非堆内存模型,该模型消除了运行时安全访问检查对系统实时性的影响,在不改变Java句法与编程模式的前提下,保留了对非堆内存多线程共享及嵌套的支持。 (2)提出了一套基于静态分析的单亲规则检查算法与赋值规则检查算法,该套算法可以在系统运行前静态完成规则检查,不对运行时系统产生影响,避免了动态分析与检查的运行时开销和实时性影响。 (3)为硬Java实时嵌入式平台设计了一种改进的分代式垃圾收集器,该收集器针对目标环境特征,提供了适用于目标环境内存管理的高效低开销的回收策略,有效避免了频繁的次级收集暂停,避免了成熟空间收集的对象移动开销和内存碎片问题。针对垃圾收集,设计了一种适用于硬Java实时嵌入式平台的对象引用模型,该模型为对象追踪、堆空间扫描、同步等提供了有效支持。 (4)为硬Java实时嵌入式平台设计了一种高效的可预测的方法调用实现模式,保证了方法调用的运行时可预测,提高了方法调用的执行效率,减少了方法调用的执行周期。
[Abstract]:With the rapid development of embedded computing and real-time computing, the embedded real time development mode is undergoing rapid changes. Compared with the traditional use of assembly language or C/C++, Java has its own advantages not only in portability, high development efficiency, low development / maintenance cost, but also to provide a higher level of abstraction. At the same time, it can meet the higher level of data modeling requirements, and it also has strong class libraries to support.Java's cross platform, object oriented, reliability, language level concurrency support, strict type check, robustness, security and so on, so that it has the basis of embedded real time development language, but standard Java is not specially for real time. With the design, it is still not able to fully meet the requirements of real time system development. It also needs to carry out the real-time extension and specification of Java. With the efforts of the real-time Java community, and the introduction of the Java real-time specification (RTSJ) and the security key Java (SCJ), the extended real-time Java has the qualification as the embedded real-time development language. At present, the research on real-time Java and its support platform has become a hot spot. There are some platforms and virtual machines that support real-time Java. Most of these platforms and virtual machines are implemented in the form of software. For the embedded real-time system with limited resources, software Java platform and virtual machine are usually due to the common reason. There are many problems, such as slow running speed, low execution efficiency and high resource overhead, and still face certain difficulties in playing Java performance advantages. Relatively speaking, using Java processor to execute bytecode directly to implement a hard Java (hard Java) engine execution mode can greatly reduce power and capital while improving operation efficiency. Source occupancy is especially suitable for embedded real-time Java applications in resource constrained environments.
This paper designs and implements a hard Java real-time embedded platform hJrep (hard Java real-time embedded platform), which can support the real time Java in a resource constrained environment. The key technologies are deeply studied and the.HJrep Java processor is used as the execution engine, and the Java byte code is used as the local instruction. The main innovative works of this paper include:
(1) a runtime predicable non heap memory model is proposed for the hard Java real-time embedded platform. This model eliminates the impact of security access check on the real-time performance of the system. Without changing the Java syntax and programming mode, it preserves the support for multithread sharing and nesting of non heap memory.
(2) a set of single parent rule checking algorithm and assignment rule checking algorithm based on static analysis is proposed. The algorithm can perform static rule checking before the system runs, and it does not affect the running time system, and avoids the running time cost and real time effect of dynamic analysis and inspection.
(3) an improved subgenerational garbage collector is designed for the hard Java real time embedded platform. The collector provides a high efficient and low cost recovery strategy for target environment memory management for target environment features. It effectively avoids the frequent secondary collection and suspension, avoids the moving overhead and memory fragmentation of the objects collected in the mature space. In view of garbage collection, an object reference model for hard Java real-time embedded platform is designed. This model provides effective support for object tracking, heap space scanning, synchronization and so on.
(4) a high efficient and predictable method of method call implementation is designed for hard Java real time embedded platform, which ensures the prediction of the running time of the method call, improves the execution efficiency of the method call and reduces the execution cycle of the method call.
【学位授予单位】：复旦大学
【学位级别】：博士
【学位授予年份】：2012
【分类号】：TP368.1
本文编号：2160276
[Abstract]:With the rapid development of embedded computing and real-time computing, the embedded real time development mode is undergoing rapid changes. Compared with the traditional use of assembly language or C/C++, Java has its own advantages not only in portability, high development efficiency, low development / maintenance cost, but also to provide a higher level of abstraction. At the same time, it can meet the higher level of data modeling requirements, and it also has strong class libraries to support.Java's cross platform, object oriented, reliability, language level concurrency support, strict type check, robustness, security and so on, so that it has the basis of embedded real time development language, but standard Java is not specially for real time. With the design, it is still not able to fully meet the requirements of real time system development. It also needs to carry out the real-time extension and specification of Java. With the efforts of the real-time Java community, and the introduction of the Java real-time specification (RTSJ) and the security key Java (SCJ), the extended real-time Java has the qualification as the embedded real-time development language. At present, the research on real-time Java and its support platform has become a hot spot. There are some platforms and virtual machines that support real-time Java. Most of these platforms and virtual machines are implemented in the form of software. For the embedded real-time system with limited resources, software Java platform and virtual machine are usually due to the common reason. There are many problems, such as slow running speed, low execution efficiency and high resource overhead, and still face certain difficulties in playing Java performance advantages. Relatively speaking, using Java processor to execute bytecode directly to implement a hard Java (hard Java) engine execution mode can greatly reduce power and capital while improving operation efficiency. Source occupancy is especially suitable for embedded real-time Java applications in resource constrained environments.
This paper designs and implements a hard Java real-time embedded platform hJrep (hard Java real-time embedded platform), which can support the real time Java in a resource constrained environment. The key technologies are deeply studied and the.HJrep Java processor is used as the execution engine, and the Java byte code is used as the local instruction. The main innovative works of this paper include:
(1) a runtime predicable non heap memory model is proposed for the hard Java real-time embedded platform. This model eliminates the impact of security access check on the real-time performance of the system. Without changing the Java syntax and programming mode, it preserves the support for multithread sharing and nesting of non heap memory.
(2) a set of single parent rule checking algorithm and assignment rule checking algorithm based on static analysis is proposed. The algorithm can perform static rule checking before the system runs, and it does not affect the running time system, and avoids the running time cost and real time effect of dynamic analysis and inspection.
(3) an improved subgenerational garbage collector is designed for the hard Java real time embedded platform. The collector provides a high efficient and low cost recovery strategy for target environment memory management for target environment features. It effectively avoids the frequent secondary collection and suspension, avoids the moving overhead and memory fragmentation of the objects collected in the mature space. In view of garbage collection, an object reference model for hard Java real-time embedded platform is designed. This model provides effective support for object tracking, heap space scanning, synchronization and so on.
(4) a high efficient and predictable method of method call implementation is designed for hard Java real time embedded platform, which ensures the prediction of the running time of the method call, improves the execution efficiency of the method call and reduces the execution cycle of the method call.
【学位授予单位】：复旦大学
【学位级别】：博士
【学位授予年份】：2012
【分类号】：TP368.1
【共引文献】
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1 刘锦锦;基于struts框架的web网站开发及数据分析[D];北京化工大学;2005年
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