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Journal of Computing Sciences in Colleges 2008年第3期23卷

作者： Carl E. Bredlau Montclair State University Montclair NJ

This paper describes an interactive implementation of a java virtual machine (JVM) simulator for interpreting java bytecodes created either from the java compiler or from an assembler such as Jasmin. Designed for ease of use, the simulator provides students with an architecture experience through the simplicity of the JVM environment.

关键词： java virtual machine architecture assembly language simulation

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Scoped types and aspects for real-time java memory management

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REAL-TIME SYSTEMS 2007年第1期37卷 1-44页

作者： Andreae, Chris Coady, Yvonne Gibbs, Celina Noble, James Vitek, Jan Zhao, Tian Purdue Univ W Lafayette IN 47907 USA Victoria Univ Wellington Wellington New Zealand Univ Wisconsin Milwaukee WI 53201 USA Univ Victoria Victoria BC Canada

Real-time systems are notoriously difficult to design and implement, and, as many real-time problems are safety-critical, their solutions must be reliable as well as efficient and correct. While higher-level programming models (such as the Real-Time Specification for java) permit real-time programmers to use language features that most programmers take for granted (objects, type checking, dynamic dispatch, and memory safety) the compromises required for real-time execution, especially concerning memory allocation, can create as many problems as they solve. This paper presents Scoped Types and Aspects for Real-Time Systems (STARS) a novel programming model for real-time systems. Scoped Types give programmers a clear model of their programs' memory use, and, being statically checkable, prevent the run-time memory errors that bedevil the RTSJ. Adopting the integrated Scoped Types and Aspects approach can significantly improve both the quality and performance of a real-time java systems, resulting in simpler systems that are reliable, efficient, and correct.

关键词： real-time systems java virtual machine memory management ownership types

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Efficient register mapping and allocation in LaTTe, an open-source java just-in-time compiler

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IEEE TRANSACTIONS ON PARALLEL AND DISTRIBUTED SYSTEMS 2007年第1期18卷 57-69页

作者： Yang, Byung-Sun Lee, Junpyo Lee, Seungll Park, Seongbae Chung, Yoo C. Kim, Suhyun Ebcioglu, Kemal Altman, Erik Moon, Soo-Mook Veloxsoft Inc Seoul 152050 South Korea Seoul Natl Univ Seoul 152050 South Korea Google Inc Mountain View CA 94043 USA Informat & Commun Univ Taejon 305732 South Korea IBM Corp Thomas J Watson Res Ctr Yorktown Hts NY 10598 USA Global Supercomp Corp Yorktown Hts NY 10598 USA Seoul Natl Univ Sch Elect Engn Seoul 151742 South Korea

java just-in-time (JIT) compilers improve the performance of a java virtual machine (JVM) by translating java bytecode into native machine code on demand. One important problem in java JIT compilation is how to map stack entries and local variables to registers efficiently and quickly, since register-based computations are much faster than memory-based ones, while JIT compilation overhead is part of the whole running time. This paper introduces LaTTe, an open-source java JIT compiler that performs fast generation of efficiently register-mapped RISC code. LaTTe first maps "all" local variables and stack entries into pseudoregisters, followed by real register allocation which also coalesces copies corresponding to pushes and pops between local variables and stack entries aggressively. Our experimental results indicate that LaTTe's sophisticated register mapping and allocation really pay off, achieving twice the performance of a naive JIT compiler that maps all local variables and stack entries to memory. It is also shown that LaTTe makes a reasonable trade-off between quality and speed of register mapping and allocation for the bytecode. We expect these results will also be beneficial to parallel and distributed java computing 1) by enhancing single-thread java performance and 2) by significantly reducing the number of memory accesses which the rest of the system must properly order to maintain coherence and keep threads synchronized.

关键词： java virtual machine just-in-time compilation register mapping register allocation copy coalescing

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Design, implementation, and evaluation of a compilation server

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ACM TRANSACTIONS ON PROGRAMMING LANGUAGES AND SYSTEMS 2007年第4期29卷 1.1-1.40页

作者： Lee, Han B. Diwan, Amer Moss, J. Eliot B. Univ Colorado Boulder CO 80309 USA Univ Massachusetts Amherst MA 01003 USA

Modern JVM implementations interleave execution with compilation of '' hot '' methods to achieve reasonable performance. Since compilation overhead impacts the execution time of the application and induces run-time pauses, we explore offloading compilation onto a compilation server. In this article, we present the design, implementation, and evaluation of a compilation server that compiles and optimizes java bytecodes on behalf of its clients. We show that the compilation server provides the following-benefits for our benchmark programs: (i) lower execution time by reducing the compilation overhead and by enabling more aggressive optimizations;(ii) lower memory allocation by eliminating allocations due to optimizing compilation and the footprint of the optimizing compiler;(iii) lower execution time of the application due to sharing of profile information across different runs of the same application and runs of different applications. We implemented the compilation server in Jikes RVM, and our results indicate that it can reduce running time by an average of 20.5%, interruptions due to compilation by an average of 81.0%, and dynamic memory allocation by 8.6% for our benchmark programs. Simulation results indicate that our current implementation of the compilation server can handle more than 50 concurrent clients while still allowing them to outperform the best performing adaptive configuration.

关键词： design experimentation performance measurement languages compilation server java virtual machine

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Reasoning about safety properties in a JVM-like environment

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SCIENCE OF COMPUTER PROGRAMMING 2007年第2-3期67卷 278-300页

作者： Fong, Philip W. L. Univ Regina Dept Comp Sci Regina SK S4S 0A2 Canada

Type-based protection mechanisms in a JVM-like environment must be administrated by the code consumer at the bytecode level. Unfortunately, formulating a sound static type system for the full JVM bytecode language can be a daunting task. It is therefore counter-productive for the designer of a bytecode-level type system to address the full complexity of the VM environment in the early stage of design. In this work, a lightweight modelling tool, Featherweight JVM, is proposed to facilitate the early evaluation of bytecode-level, type-based protection mechanisms and, specifically, their ability to enforce security-motivated stack invariants and confinement properties. Rather than modelling the execution of a specific bytecode stream, Featherweight JVM is a nondeterministic event model that captures all the possible access event sequences that may be generated by a JVM-like environment when well-typed bytecode programs are executed. The effect of deploying a type-based protection mechanism can be modelled by a safety policy that constrains the event sequences produced by the VM model. To evaluate the effectiveness of the protection mechanism, security theorems in the form of state invariants can then be proved in the policy-guarded VM model. To demonstrate the utility of the proposed approach, Vitek et al.'s Confined Types has been formulated as a safety policy for the Featherweight JVM, and a corresponding confinement theorem has been established. To reduce class loading overhead, a capability-based reformulation of Confined Types is then studied, and is shown to preserve the confinement theorem. This paper thus provides first evidence on the utility of Featherweight JVM in providing early feedback to the designer of type-based protection mechanisms for JVM-like environments. (c) 2007 Elsevier B.V. All rights reserved.

关键词： java virtual machine type-based protection mechanism formal verification safety access control stack invariant confinement

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java client ahead-of-time compiler for embedded systems 07

Java client ahead-of-time compiler for embedded systems

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Conference on Languages, Compilers and Tools for Embedded Systems

作者： Hong, Sunghyun Kim, Jin-Chul Shin, Jin Woo Moon, Soo-Mook Oh, Hyeong-Seok Lee, Jaemok Choi, Hyung-Kyu Seoul Natl Univ Sch Elect Engn & Comp Sci Seoul 151742 South Korea

ISBN: (纸本)9781595936325

The performance of embedded java virtual machine can be improved by ahead-of-time compiler ( AOTC), which translates bytecode into machine code in the server and installs the machine code on the client device. Although AOTC is more advantageous than just-in-time compiler (JITC) due to its absence of the translation overhead, AOTC cannot be applicable to dynamically downloaded classes at runtime. This paper proposes client-AOTC (c-AOTC) which performs AOTC on the client device using the JITC module installed on the device, complementing the server-AOTC. The machine code of a method translated by JITC is cached on a persistent memory of the device, and when the method is invoked again in a later run of the program, the machine code is loaded and executed directly without the translation and interpretation overhead. One of major issues in c-AOTC is relocation because some of the addresses used by the cached machine code are not correct when the machine code is loaded and used in a different run;those addresses should be corrected before they are used. Constant pool resolution and inlining complicate the relocation problem and we propose our solutions. We developed a c-AOTC on Sun's CDC VM reference implementation ( RI) and our evaluation results indicate that cAOTC can improve the performance significantly, as much as an average of 12%. We also experiment with the issue of reducing the number of c-AOTC methods to be cached when the persistent space is tight, with a graceful degradation of performance.

关键词： java ahead-of-time compiler just-in-time compiler relocation early binding java virtual machine J2ME CDC performance experimentation languages

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StreamFlex: High-throughput stream programming in java 07

StreamFlex: High-throughput stream programming in Java

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22nd International Conference on Object-Oriented Programming, Systems, Languages and Applications

作者： Spring, Jesper H. Privat, Jean Guerraoui, Rachid Vitek, Jan Ecole Polytech Fed Lausanne Lausanne Switzerland Purdue Univ Dept Comp Sci W Lafayette IN 47907 USA IBM Corp San Jose CA 95114 USA

ISBN: (纸本)9781595937865

The stream programming paradigm aims to expose coarse-grained parallelism in applications that must process continuous sequences of events. The appeal of stream programming comes from its conceptual simplicity. A program is a collection of independent filters which communicate by the means of uni-directional data channels. This model lends itself naturally to concurrent and efficient implementations on modern multiprocessors. As the output behavior of filters is determined by the state of their input channels, stream programs have fewer opportunities for the errors (such as data races and deadlocks) that plague shared memory concurrent programming. This paper introduces STREAMFLEX, an extension to java which marries streams with objects and thus enables to combine, in the same java virtual machine, stream processing code with traditional object-oriented components. STREAMFLEX targets high-throughput low-latency applications with stringent quality-of-service requirements. To achieve these goals, it must, at the same time, extend and restrict java. To allow for program optimization and provide latency guarantees, the STREAMFLEX compiler restricts java by imposing a stricter typing discipline on filters. On the other hand, STREAMFLEX extends the java virtual machine with real-time capabilities, transactional memory and type-safe region-based allocation. The result is a rich and expressive language that can be implemented efficiently.

关键词： languages experimentation. real-time systems java virtual machine memory management ownership types stream processing

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Performance evaluation of embedded garbage collectors in CVM environment

Performance evaluation of embedded garbage collectors in CVM...

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11th International Conference on Knowledge-Based Intelligent Informational and Engineering Systems/17th Italian Workshop on Neural Networks

作者： Chal, Chang-Il Kim, Sang-Wook Chang, Ji-Woong Shin, Miyoung Hanyang Univ Dept Informat & Commun Seoul South Korea Korea Polytech Univ Dept Game & Multimedia Engn Seongnam Si South Korea Kyungpook Natl Univ Sch Elect Engn & Comp Sci Daegu South Korea

ISBN: (纸本)9783540748175

Garbage collection in the java virtual machine is a core function that relieves application programmers of difficulties related to memory management. In this paper, we evaluate the performance of GenGC and GenRGC, garbage collectors for the embedded java virtual machine, CVM. To compare the performance of GenGC and GenRGC, we first evaluate the execution time of garbage collection and the delay time caused by garbage collection. Second, for more detailed performance analysis of GenRGC, we evaluate the execution time of garbage collection and the delay time caused by garbage collection while changing the sizes of a block and a frame. Third, we analyze the size of storage space required for performing GenRGC, and show GenRGC to be suitable for embedded environment with a limited amount of memory. Since CVM is the most representative one of embedded java virtual machines, this performance study is quite meaningful in that we can predict the performance of garbage collectors in real application environments more accurately.

关键词： java java virtual machine garbage collection CVM

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Reflexes: Abstractions for Highly Responsive Systems 07

Reflexes: Abstractions for Highly Responsive Systems

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3rd International Conference on virtual Execution Environments

作者： Spring, Jesper Honig Pizo, Filip Guerraoui, Rachid Vitek, Jan Ecole Polytech Fed Lausanne CH-1015 Lausanne Switzerland

ISBN: (纸本)9781595936301

Commercial java virtual machines are designed to maximize the performance of applications at the expense of predictability. High throughput garbage collection algorithms, for example, can introduce pauses of 100 milliseconds or more. We are interested in supporting applications with response times in the tens of microseconds and their integration with larger timing-oblivious applications in the same java virtual machine. We propose Reflexes, a new abstraction for writing highly responsive systems in java and investigate the virtual machine support needed to add Reflexes to a java environment. Our implementation of Reflexes was evaluated on several programs including an audio-processing application. We were able to run a Reflex at 22.05KHz with less than 0.2% missed deadlines over 10 million observations, a result that compares favorably to an implementation written in C.

关键词： Real-time systems java virtual machine Memory management Ownership types

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java client ahead-of-time compiler for embedded systems

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ACM SIGPLAN NOTICES 2007年第7期42卷 63-72页

作者： Hong, Sunghyun Kim, Jin-Chul Shin, Jin Woo Moon, Soo-Mook Oh, Hyeong-Seok Lee, Jaemok Choi, Hyung-Kyu Seoul Natl Univ Sch Elect Engn & Comp Sci Seoul 151742 South Korea

关键词： java ahead-of-time compiler just-in-time compiler relocation early binding java virtual machine J2ME CDC performance experimentation languages

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