Java Native Interface idioms for C++ class hierarchies

The Java^TM Native Interface (JNI) provides a set of mechanisms for implementing Java methods in C or C++. JNI is useful for reusing C and C++ code repositories within Java frameworks. JNI is also useful for real‐time systems, where compiled C/C++ code executes performance‐critical tasks, while Java code executes system control and feature tasks. Available JNI literature concentrates on creating Java proxy classes that allow Java clients to interact with C++ classes. Current JNI literature does not discuss Java proxies for entire C++ inheritance hierarchies; that is the topic of this paper. Our experience in reusing C++ class hierarchies within a Java framework has uncovered a set of useful techniques for constructing Java proxy class hierarchies that mirror their C++ counterparts. This report gives both high level design guidelines and specific programming idioms for constructing Java class hierarchies that serve as proxies for C++ counterparts. We begin by discussing opportunities for reuse within a proxy class hierarchy, as well as problems caused by differences between the Java and C++ approaches to inheritance. The two most significant differences are due to C++ support for invocation of a member function based on the static type of its class, and C++ support for multiple implementation inheritance. Two example C++ class hierarchies provide the basis for a set of sections that present the design guidelines and that codify the programming idioms. This work could serve as the basis for an automatic generator of Java proxy class hierarchies. Copyright © 2000 John Wiley & Sons, Ltd.     

A type system for static and dynamic checking of C++ pointers

Object-oriented programming is the most used programming paradigm when dealing with large-scale, modular software. In this field, the two leading languages are Java and C++. The former has superior qualities in terms of safety and ease of programming, whereas the latter is often considered an “old” language, too complex and potentially unsafe.In this paper, we describe a new type system designed to analyze the security problems derived from pointer manipulation in C++. This type system tries to trap the most common errors through static analysis, i.e., at compile-time, and only when static analysis fails it generates and embeds code fragments that apply runtime checks on specific instructions. The aim of this new type system is to give C++ the same safety of Java in the most important memory-related operations, without adding much runtime overhead. An experimental implementation of the type system is also presented, embedded in a C++ analysis tool called GPCC.     

Scientific computing with Java and C++: a case study using functional magnetic resonance neuroimages

Modern systems for the analysis of image‐based biomedical data, such as functional magnetic resonance imaging (fMRI), require fast computational techniques and rapid, robust development. Object‐oriented programming languages such as Java and C++ provide the foundations for the development of complex data analysis applications. This case study explores the advantages and disadvantages of using these two programming environments for scientific computation as typified in the analysis of fMRI datasets. C++ is well suited for computational and memory optimization while Java is more compliant to the object‐oriented paradigm, supports cross‐platform development and has a rich set of application programming interface (API) classes. The same data model and algorithms were implemented in C++ and Java, and a user interface was developed with the Java API. Comparisons were made with respect to computational performance and ease of development. Benchmarks show that C++ generally outperforms Java, while Java is easier to use, leading to more robust code and shorter development times. However, with the advent of newer just‐in‐time compilers, Java performance is at times comparable to C++. The latest Java virtual machine technology is closing the gap and eventually Java should be a good compromise between efficient algorithm performance and effective application development. Copyright © 2004 John Wiley & Sons, Ltd.     

Arachne: a portable threads system supporting migrant threads onheterogeneous network farms

We present the design and implementation of Arachne, a threads system that can be interfaced with a communications library for multithreaded distributed computations. In particular, Arachne supports thread migration between heterogeneous platforms, dynamic stack size management, and recursive thread functions. Arachne is efficient, flexible, and portable-it is based entirely on C and C++. To facilitate heterogeneous thread operations, we have added three keywords to the C++ language. The Arachne preprocessor takes as input code written in that language and outputs C++ code suitable for compilation with a conventional C++ compiler. The Arachne runtime system manages all threads during program execution. We present some performance measurements on the costs of basic thread operations and thread migration in Arachne and compare these to costs in other threads systems     

A comparative study of Java and C performance in two large‐scale parallel applications

In the 1990s the Message Passing Interface Forum defined MPI bindings for Fortran, C, and C++. With the success of MPI these relatively conservative languages have continued to dominate in the parallel computing community. There are compelling arguments in favour of more modern languages like Java. These include portability, better runtime error checking, modularity, and multi‐threading. But these arguments have not converted many HPC programmers, perhaps due to the scarcity of full‐scale scientific Java codes, and the lack of evidence for performance competitive with C or Fortran. This paper tries to redress this situation by porting two scientific applications to Java. Both of these applications are parallelized using our thread‐safe Java messaging system—MPJ Express. The first application is the Gadget‐2 code, which is a massively parallel structure formation code for cosmological simulations. The second application uses the finite‐domain time‐difference method for simulations in the area of computational electromagnetics. We evaluate and compare the performance of the Java and C versions of these two scientific applications, and demonstrate that the Java codes can achieve performance comparable with legacy applications written in conventional HPC languages. Copyright © 2009 John Wiley & Sons, Ltd.     

Experiences building a communication‐oriented JavaOS

Mobile code makes it easier to maintain, debug, update, and customize a system. Active networks are one of the more interesting applications of mobile code: code is injected into the nodes of a network to customize the network's functionality, such as routing, and to add new features, such as special‐purpose congestion control and filtering algorithms. The challenge is to develop a communication‐oriented platform for such systems. We refer to mobile code targeted at low‐level, communication‐oriented systems like active networks as liquid software, the key distinction being that liquid software is focused on the efficient transfer of data, not high‐performance computation. To this end, we have designed and implemented Joust, which consists of a complete re‐implementation of the Java virtual machine (including both the runtime system and a just‐in‐time compiler), running on the Scout operating system (a configurable, communication‐oriented OS). The result is a configurable, high‐performance platform for running liquid software. We present the results of implementing two different applications of liquid software on Joust, including a prototype architecture for active networks. Copyright © 2000 John Wiley & Sons, Ltd.     

MRPC: A high performance RPC system for MPMD parallel computing

MRPC is an RPC system that is designed and optimized for MPMD parallel computing. Existing systems based on standard RPC incur an unnecessarily high cost when used on high‐performance multi‐computers, limiting the appeal of RPC‐based languages in the parallel computing community. MRPC combines the efficient control and data transfer provided by Active Messages (AM) with a minimal multithreaded runtime system that extends AM with the features required to support MPMD. This approach introduces only the necessary RPC overheads for an MPMD environment. MRPC has been integrated into Compositional C++ (CC++), a parallel extension of C++ that offers an MPMD programming model. Basic performance in MRPC is within a factor of two from those of Split‐C, a highly tuned SPMD language, and other messaging layers. CC++ applications perform within a factor of two to six from comparable Split‐C versions, which represent an order of magnitude improvement over previous CC++ implementations. Copyright © 1999 John Wiley & Sons, Ltd.     

Platform‐independent profiling in a virtual execution environment

Virtual execution environments, such as the Java virtual machine, promote platform‐independent software development. However, when it comes to analyzing algorithm complexity and performance bottlenecks, available tools focus on platform‐specific metrics, such as the CPU time consumption on a particular system. Other drawbacks of many prevailing profiling tools are high overhead, significant measurement perturbation, as well as reduced portability of profiling tools, which are often implemented in platform‐dependent native code. This article presents a novel profiling approach, which is entirely based on program transformation techniques, in order to build a profiling data structure that provides calling‐context‐sensitive program execution statistics. We explore the use of platform‐independent profiling metrics in order to make the instrumentation entirely portable and to generate reproducible profiles. We implemented these ideas within a Java‐based profiling tool called JP. A significant novelty is that this tool achieves complete bytecode coverage by statically instrumenting the core runtime libraries and dynamically instrumenting the rest of the code. JP provides a small and flexible API to write customized profiling agents in pure Java, which are periodically activated to process the collected profiling information. Performance measurements point out that, despite the presence of dynamic instrumentation, JP causes significantly less overhead than a prevailing tool for the profiling of Java code. Copyright © 2008 John Wiley & Sons, Ltd.     

A compiler for exploiting nested parallelism in OpenMP programs

This paper presents the design and implementation of a parallelization framework and OpenMP runtime support in Intel^® C++ & Fortran compilers for exploiting nested parallelism in applications using OpenMP pragmas or directives. We conduct the performance evaluation of two multimedia applications parallelized with OpenMP pragmas and compiled with the Intel C++ compiler on Hyper-Threading Technology (HT) enabled multiprocessor systems. The performance results show that the multithreaded code generated by the Intel compiler achieved a speedup up to 4.69 on 4 processors with HT enabled for five different input video sequences for the H.264 encoder workload, and a 1.28 speedup on an HT enabled single-CPU system and 1.99 speedup on an HT-enabled dual-CPU system for the audio–visual speech recognition workload. The performance gain due to exploiting nested parallelism for leveraging Hyper-Threading Technology is up to 70% for two multimedia workloads under different multiprocessor system configurations. These results demonstrate that hyper-threading benefits can be achieved by exploiting nested parallelism through Intel compiler and runtime system support for OpenMP programs.     

Automatic detection and masking of nonatomic exception handling

The development of robust software is a difficult undertaking and is becoming increasingly more important as applications grow larger and more complex. Although modern programming languages such as C++ and Java provide sophisticated exception handling mechanisms to detect and correct runtime error conditions, exception handling code must still be programmed with care to preserve application consistency. In particular, exception handling is only effective if the premature termination of a method due to an exception does not leave an object in an inconsistent state. We address this issue by introducing the notion of failure atomicity in the context of exceptions. We propose practical techniques to automatically detect and mask the nonatomic exception handling situations encountered during program execution. These techniques can be applied to applications written in various programming languages that support exceptions. We perform experimental evaluation on both C++ and Java applications to demonstrate the effectiveness of our techniques and measure the overhead that they introduce.     

Accurate garbage collection in uncooperative environments revisited

Implementing a concurrent programming language such as Java by means of a translator to an existing language is attractive as it provides portability over all platforms supported by the host language and reduces development time—as many low‐level tasks can be delegated to the host compiler. The C and C++ programming languages are popular choices for many language implementations due to the availability of efficient compilers on a wide range of platforms. For garbage‐collected languages, however, they are not a perfect match as no support is provided for accurately discovering pointers to heap‐allocated data on thread stacks. We evaluate several previously published techniques and propose a new mechanism, lazy pointer stacks, for performing accurate garbage collection in such uncooperative environments. We implemented the new technique in the Ovm Java virtual machine with our own Java‐to‐C/C++ compiler using GCC as a back‐end compiler. Our extensive experimental results confirm that lazy pointer stacks outperform existing approaches: we provide a speedup of 4.5% over Henderson's accurate collector with a 17% increase in code size. Accurate collection is essential in the context of real‐time systems, we thus validate our approach with the implementation of a real‐time concurrent garbage collection algorithm. Copyright © 2009 John Wiley & Sons, Ltd.     

Babylon: middleware for distributed,parallel, and mobile Java applications

Babylon is a collection of tools and services that provide a 100% Java‐compatible environment for developing, running and managing parallel, distributed and mobile Java applications. It incorporates features such as object migration, asynchronous method invocation, and remote class loading, while providing an easy‐to‐use interface. Additionally, Babylon enables Java applications to seamlessly create and interact with remote objects, while protecting those objects from other applications by implementing access restrictions and separate namespaces. The implementation of Babylon centers around dynamic proxies, a feature first available in Java 1.3, that allow proxy objects to be created at runtime. Dynamic proxies play a key role in achieving the goals of Babylon. The potential cluster computing benefits of the system are demonstrated with experimental results, which show that sequential Java applications can achieve significant performance benefits from using Babylon to parallelize their work across a cluster of workstations. Copyright © 2008 John Wiley & Sons, Ltd.     

Dynamic Event Generation for Runtime Checking using the JDI

Approaches to runtime checking have to track the execution of a software system and therefore have to deal with generating and processing execution events. Often these techniques are applied at the code level – either by inserting new source code prior to the compilation or by modifying the target code, e.g. Java byte code, before running the program.The jassda [4,3] framework and tool enable runtime checking of Java programs against a CSP-like specification. For generating events it uses the Java Debug Interface (JDI) and thus no modifications to the code are necessary. Another advantage is that events are generated on demand, i.e. dynamically at runtime it is determined which events to generate for the current debug run without modifying the program itself. This paper shows how this event generation is done by the jassda framework.     

Parallel programming on a high‐performance application‐runtime

High‐performance application development remains challenging, particularly for scientists making the transition to a heterogeneous grid environment. In general areas of computing, virtual environments such as Java and .Net have proved to be successful in fostering application development, allowing users to target and compile to a single environment, rather than a range of platforms, instruction sets and libraries. However, existing runtime environments are focused on business and desktop computing and they do not support the necessary high‐performance computing (HPC) abstractions required by e‐Scientists. Our work is focused on developing an application‐runtime that can support these services natively. The result is a new approach to the development of an application‐runtime for HPC: the Motor system has been developed by integrating a high‐performance communication library directly within a virtual machine. The Motor message passing library is integrated alongside and in cooperation with other runtime libraries and services while retaining a strong message passing performance. As a result, the application developer is provided with a common environment for HPC application development. This environment supports both procedural languages, such as C, and modern object‐oriented languages, such as C#. This paper describes the unique Motor architecture, presents its implementation and demonstrates its performance and use. Copyright © 2008 John Wiley & Sons, Ltd.     

XQuery语言Hotspot编译系统的支撑框架

设计并实现XQuery语言Hotspot编译系统的支撑框架,通过对XQuery程序进行Hotspot分析,将执行频率高的程序模块编译为Java字节码,以提高程序执行效率。实验结果证明,Hotspot编译系统在执行效率上相比解释系统有一定提高,与静态编译系统相比,能更有效地处理网络上动态生成的XQuery查询。     

VCluster: a thread‐based Java middleware for SMP and heterogeneous clusters with thread migration support

Clusters, composed of symmetric multiprocessor (SMP) machines and heterogeneous machines, have become increasingly popular for high‐performance computing. Message‐passing libraries, such as message‐passing interface (MPI) and parallel virtual machine (PVM), are de facto parallel programming libraries for clusters that usually consist of homogeneous and uni‐processor machines. For SMP machines, MPI is combined with multithreading libraries like POSIX Thread and OpenMP to take advantage of the architecture. In addition to existing parallel programming libraries that are in C/C++ and FORTRAN programming languages, the Java programming language presents itself as another alternative with its object‐oriented framework, platform neutral byte code, and ever‐increasing performance. This paper presents a new parallel programming model and a library, VCluster, which implements this model. VCluster is based on migrating virtual threads instead of processes to support clusters of SMP machines more efficiently. The implementation uses thread migration, which can be used in dynamic load balancing. VCluster was developed in pure Java, utilizing the portability of Java to support clusters of heterogeneous machines. Several applications are developed to illustrate the use of this library and compare the usability and performance of VCluster with other approaches. Copyright © 2007 John Wiley & Sons, Ltd.     

Compilers for improved Java performance

Because they are interpreted, Java executables run slower than their compiled counterparts. The native executable translation (NET) compiler's objective is to optimize the translation of Java byte-code to native machine code so that it runs nearly as fast as native code generated directly from a source. The article presents some preliminary results for several large application programs and standard benchmarks. It compares the NET-compiled code performance with Sun's Java VM, Microsoft's Java just-in-time compiler, and equivalent C and C++ programs directly compiled. The results show that the optimizing NET compiler is capable of achieving better performance than the two other byte-code execution methods, in some cases achieving speeds comparable to directly compiled native code     

On Efficiency and Optimization of C++ Programs

The efficiency of object-oriented programs has become a point of great interest. One necessary factor for program efficiency is the optimization techniques involved. This paper presents the performance of several variations of a given C++ program and compares them with a version that uses no object-oriented features. Our result indicates that some object-oriented features in C++ are not well optimized in current C++ compilers. We thus discuss some code optimization techniques that can improve the efficiency based on the given C++ program.