Java Grande 1999 Special Issue of Concurrency:Practice and Experience

Editorial is at editorialjg99.html

Original Conference URL http://www.cs.ucsb.edu/conferences/java99/

• C413: Locality optimization in JavaParty by means of static type analysis
  • Abstract: On clusters and DMPs, locality of objects and threads and hence avoidance of network communication, are crucial for performance. We show that an extension of known type inference mechanisms can be used to compute placement decisions that improve locality. In addition to this general contribution, the paper specifically addresses the problems that are caused by the distributed Java environment. Since the JVM is assumed to be fixed, the optimization is done as source- to-source transformation.
  • Michael Philippsen and Bernhard Haumacher University of Karlsruhe, Germany
  • phlipp@ira.uka.de and hauma@ira.uka.de
  • Resubmit PDF: C413JGFSIphilipFINAL/resubmit/static.pdf
• C414: More Efficient Serialization and RMI for Java
  • Abstract:. In current Java implementations, Remote Method Invoca- tion (RMI) is too slow, especially for high performance computing. RMI is designed for wide-area and high-latency networks, it is based on a slow object serialization, and it does not support high-performance commu- nication networks. The paper demonstrates that a much faster drop-in RMI and an ecient drop-in serialization can be designed and implemented completely in Java without any native code. Moreover, the re-designed RMI supports non- TCP/IP communication networks, even with heterogeneous transport protocols. We demonstrate that for high performance computing some of the official serialization's generality can and should be traded for speed. As a by-product, a benchmark collection for RMI is presented. On PCs connected through Ethernet, the better serialization and the improved RMI save a median of 45% (maximum of 71%) of the runtime for some set of arguments. On our Myrinet-based ParaStation network (a cluster of DEC Alphas) we save a median of 85% (maximum of 96%), compared to standard RMI, standard serialization, and Fast Ethernet; a remote method invocation runs as fast as 80 mus round trip time, compared to about 1.5 ms.
  • Michael Philippsen, Bernhard Haumacher, and Christian Nester
  • Computer Science Department, University of Karlsruhe Am Fasanengarten 5, 76128 Karlsruhe, Germany
  • [phlipp,hauma,nester]@ira.uka.de
  • http://wwwipd.ira.uka.de/JavaParty/
  • Resubmit PDF: C414JGFSIphilipFINAL/c414serialrmiresubmit/serialrmi.pdf
• C423: Jaguar: Enabling Efficient Communication and I/O in Java
  • Abstract: Implementing efficient communication and I/O mechanisms in Java requires both fast access to low-level system resources (such as network and raw disk interfaces) and direct manipulation of memory regions external to the Java heap (such as communication and I/O buffers). Java native methods are too expensive to perform these operations and raise serious protection concerns. We present Jaguar, a new mechanism which provides Java applications with efficient access to system resources while retaining the protection of the Java environment. This is accomplished through compile-time translation of certain Java bytecodes to inlined machine code segments. We demonstrate the use of Jaguar through a Java interface to the VIA fast communications layer, which achieves nearly identical performance to that of C, and Pre-Serialized Objects, a mechanism which greatly reduces the cost of Java object serialization.
  • Matt Welsh and David Culler
  • University of California, Berkeley
  • mdw,culler@cs.berkeley.edu
  • Resubmit PDF: C423JGFSIWelshFINAL/jaguar-journal.pdf
• C424: Performance Measurement of Dynamically Compiled Java Executions
  • Abstract With the development of dynamic compilers for Java, Java’s performance promises to rival that of equivalent C/C++ binary executions. This should ensure that Java will become the platform of choice for ubiquitous Web-based supercomputing. Therefore, being able to build performance tools for dynamically compiled Java executions will become increasingly important. In this paper we discuss those aspects of dynamically compiled Java executions that make performance measurement difficult: (1) some Java application methods may be transformed from byte-code to native code at run-time; and (2), even in native form, application code may interact with the Java virtual machine. We describe Paradyn-J, an experimental version of the Paradyn Parallel Performance Tool that addresses this environment by describing performance data from dynamically compiled executions in terms of the multiple execution forms (interpreted byte-code and directly executed native code) of a method, costs of the dynamic compilation, and costs of residual dependencies of the application on the virtual machine. We use performance data from Paradyn-J to tune a Java application method, and improve its interpreted byte-code execution by 11% and its native form execution by 10%. As a result of tuning just one method, we improve the application’s total execution time by 10% when run under Sun’s ExactVM (included in the Platform2 release of JDK). Results of our work are guide to virtual machine designers as what type of performance data should be available through Java VM performance tool APIs.
  • Tia Newhall and Barton P. Miller
  • {newhall,bart}@cs.wisc.edu
  • Computer Sciences Department University of Wisconsin Madison, WI 53706-1685
  • Resubmit PDF: C424JGFSINewhallFINAL/c424resubmit.pdf
• C426: The Gateway System: Uniform Web Based Access to Remote Resources
  • Abstract: Exploiting our experience developing the WebFlow system, we designed the Gateway system to provide seamless and secure access to computational resources at ASC MSRC. The Gateway follows our commodity components strategy, and it is implemented as a modern three-tier system. Tier 1 is a high-level front end for visual programming, steering, run-time data analysis and visualization that is built on top of the Web and OO commodity standards. Distributed object-based, scalable, and reusable Web server and Object broker middleware forms Tier 2. Back-end services comprise Tier 3. In particular, access to high-performance computational resources is provided by implementing the emerging standard for metacomputing API.
  • Tomasz Haupt, Erol Akarsu, Geoffrey Fox, Alexey Kalinichenko, Kang-Seok Kim, Praveen Sheethalnath, Choon-Han Youn
  • Northeast Parallel Architecture Center at Syracuse University
  • haupt@npac.syr.edu
  • Resubmit PDF:C426JGFSIhaupt/JavaGrande99-submit.pdf
• C427: Object Serialization for Marshalling Data in a Java Interface to MPI
  • Abstract: Several Java bindings to Message Passing Interface (MPI) software have been developed recently. Message buers have usually been restricted to arrays with elements of primitive type. We discuss adoption of the Java object serialization model for marshalling general communication data in MPI-like APIs. This approach is compared with a Java transcription of the standard MPI derived datatype mechanism. We describe an imple- mentation of the mpiJava interface to MPI that incorporates automatic object serialization. Benchmark results conrm that current JDK im- plementations of serialization are not fast enough for high performance messaging applications. Means of solving this problem are discussed, and benchmarks for greatly improved schemes are presented.
  • Bryan Carpenter, Geoffrey Fox, Sung Hoon Ko and Sang Lim
  • NPAC at Syracuse University Syracuse, NY 13244
  • {dbc,gcf,shko,slim}@npac.syr.edu
  • Resubmit PDF: C427JGFSIdbcFINAL/c427resubmit.pdf
• C428: Wide-Area Parallel Programming using the Remote Method Invocation Model
  • Abstract: Java’s support for parallel and distributed processing makes the language attractive for metacomputing applications, such as parallel applications that run on geographically distributed (wide-area) systems. To obtain actual experience with a Java-centric approach to metacomput-ing, we have built and used a high-performance wide-area Java system, called Manta. Manta implements the Java Remote Method Invocation (RMI) model using different communication protocols (active messages and TCP/IP) for different networks. The paper shows how wide-area parallel applications can be expressed and optimized using Java RMI. Also, it presents performance results of several applications on a wide-area system consisting of four Myrinet-based clusters connected by ATMWANs. We finally discuss alternative programming models, namely object replication, JavaSpaces, and MPI for Java.
  • Rob van Nieuwpoort, Jason Maassen, Henri E. Bal, Thilo Kielmann, Ronald Veldema
  • Department of Computer Science, Vrije Universiteit, Amsterdam, The Netherlands.
  • rob@cs.vu.nl, jason@cs.vu.nl, bal@cs.vu.nl, kielmann@cs.vu.nl, rveldema@cs.vu.nl
  • http://www.cs.vu.nl/albatross/
  • Resubmit PDF: C428JGFSIbalFINAL/jgfsi_c428/cpe99.pdf
• C429: Performance Limitations of the Java Core Libraries
  • Abstract: Unlike applets, traditional systems programs written in Java place significant demands on the Java runtime and core libraries, and their performance is often critically important. This paper describes our experiences using Java to build such a systems program, namely, a high-performance web crawler. We found that our runtime, which includes a just-in-time compiler that compiles Java bytecodes to native machine code, performed well. However, we encountered several performance problems with the Java core libraries, including excessive synchronization, excessive allocation, and other programming inefficiencies. The paper describes the most serious pitfalls and how we programmed around them. In total, these workarounds more than doubled the speed of our crawler.
  • Allan Heydon, Marc Najork
  • Compaq Computer Corporation, Systems Research Center, 130 Lytton Avenue, Palo Alto, CA 94301, USA
  • {heydon,najork}@pa.dec.com
  • Resubmit PDF: C429JGFSIheydonFINAL/c429resubmit.pdf
• C430:A Java/CORBA based Visual Program Composition Environment for PSEs
  • Abstract: A Problem Solving Environment (PSE) is a complete, integrated com- puting environment for composing, compiling and running applications in a specic problem area or domain. A Visual Programming Composition Environment (VPCE) is described, which serves as a user interface for a PSE, and uses Java and CORBA to provide a framework of tools to enable the construction of scientic applications from components. The VPCE consists of a component repository, from which the user can select o-the-shelf or in-house components, a graphical composition area on which components can be combined, various tools that facilitate the conguration of components, the integration of legacy codes into com- ponents and the design and building of new components. The VPCE produces output using data ow techniques in the form of a task graph, annotated with a performance model plus constraints for each component, expressed in XML. In addition, the VPCE supports a domain specic expert system based on JESS [9] to guide the user in component selection and to perform integrity checking.
  • Matthew S. Shields, Omer F. Rana, David W. Walker, Maozhen Li
  • Department of Computer Science, Cardiff University, POBox 916, Cardiff, CF24 3XF, UK
  • David Golby
  • Department of Mathematical Modelling, British Aerospace Sowerby Research Center, PO Box 5, Filton, Bristol, BS34 7QW, UK
  • Omer F Rana <O.F.Rana@cs.cf.ac.uk>
  • Resubmit PDF: C430JGFSIranaFINAL/shields-rana-walker-li-golby-final.pdf
• C431:Ajents: Towards an Environment for Parallel, Distributed and Mobile Java Applications
  • Abstract: The rapid proliferation of the World-Wide Web has been due to the seamless access it provides to information that is distributed both within organizations and around the world. In this paper, we describe the design and implementation of a system, called Ajents, which provides the software infras- tructure necessary to support a similar level of seamless ac- cess to organization-wide or world-wide heterogeneous com- puting resources. Ajents introduces class libraries which are written en- tirely in Java and that run on any standard compliant Java virtual machine. These class libraries implement and com- bine several important features that are essential to sup- porting distributed and parallel computing using Java. Such features include: the ability to easily create objects on re- mote hosts, interact with those objects through either syn- chronous or asynchronous remote method invocations, and to freely migrate objects to heterogeneous hosts. Our experimental results show that in our test environ- ment: we are able to achieve good speedup on a sample parallel application; the overheads introduced by our imple- mentation do not adversely aect remote method invocation times; and (somewhat surprisingly) the cost of migration does not greatly impact the execution time of an example application.
  • Matthew Izatt, Patrick Chan
  • Department of Computer Science York University, Toronto, Ontario, M3J 1P3
  • {izatt,y-chan}@cs.yorku.ca
  • Tim Brecht Department of Computer Science University of Waterloo, Waterloo, Ontario, N2L 3G1
  • brecht@cs.uwaterloo.ca
  • Resubmit PDF: C431JGFSIbrechtFINAL/c431resubmit.pdf
• C432: A Mobile Agent Based Push Methodology for Global Parallel Computing
  • Abstract: The 1990s are seeing the explosive growth of the Internet and Web-based information sharing and dissemination systems. The Internet is also showing a potential of forming of a supercomputing resource out of networked computers. Metacomputing on the Internet often works in a machine-centric “pull” execution model. That is, a coordinator machine maintains a pool of tasks and distributes the tasks to other participants on demand. This paper proposes a novel mobile agent based “push” methodology from the perspective of applications. In the method, users declare their compute-bound jobs as autonomous agents. The computational agents will roam on the Internet to find servers to run. Since the agents can be programmed to satisfy their goals, even if they move and lose contact with their creators, they can survive intermittent or unreliable network connection. Dur-ing their lifetime, the agents can also move themselves autonomously from one machine to another for load balancing, enhancing data locality, and tolerating faults. We present an agent-oriented programming and resource brokerage infrastructure, TRAVELER, in support of wide area parallel applications. TRAVELER provides a mecha-nism for clients to wrap their parallel applications as mobile agents. It allows clients to dispatch their computational agents via a resource broker. The broker forms a parallel virtual machine atop servers to execute the agents. TRAVELER relies on an integrated dis-tributed shared array runtime system to support agent communications on clusters of servers. We demonstrated the feasibility of the TRAVELER in parallel sorting and LU factorization problems.
  • Cheng-Zhong Xu and Brian Wims
  • Department of Electrical and Computer Engineering Wayne State University, Detroit, MI 48202
  • czxu@ece.eng.wayne.edu
  • Resubmit PDF: C432JGFSIxuFINAL/c432resubmit.pdf
• C433:A Tale of Two Directories: Implementing Distributed Shared Objects in Java
  • Abstract: A directory service keeps track of the location and status of mobile objects in a distributed system. This paper describes our experience im- plementing two distributed directory protocols as part of the Aleph toolkit, a distributed shared object system implemented in Java. One protocol is a conventional home-based protocol, in which a xed node keeps track of the object's location and status. The other is a novel arrow protocol, based on a simple path-reversal algorithm. We were surprised to discover that the arrow protocol outperformed the home protocol, sometimes substantially, across a range of system sizes. This paper describes a series of experiments testing whether the discrep- ancy is due to an artifact of the Java run-time system (such as dierences in thread management or object serialization costs), or whether it is some- thing inherent in the protocols themselves. In the end, we use insights gained from these experimental results to design a new directory protocol
  • Maurice Herlihy
  • Computer Science Department Brown University Providence, RI 02912
  • herlihy@cs.brown.edu
  • Michael P. Warres
  • Sun Microsystems
  • mpw@east.sun.com
  • Resubmit PDF:C433JGFSIherlihy/c433resubmit.pdf
• C434:A Benchmark Suite for High Performance Java
  • Abstract: Increasing interest is being shown in the use of Java for large scale or Grande applications. This new use of Java places specic demands on the Java execution environments that could be tested and compared using a standard benchmark suite. We describe the design and implementation of such a suite, paying particular attention to Java-specic issues. Sample results are presented for a number of implementa- tions of the Java Virtual Machine (JVM).
  • J. M. Bull, L. A. Smith, M. D. Westhead, D. S. Henty and R. A. Davey
  • EPCC, James Clerk Maxwell Building, The King's Buildings, The University of Edinburgh, Mayfield Road, Edinburgh EH9 3JZ, Scotland, U.K.
  • epcc-javagrande@epcc.ed.ac.uk
  • markb@epcc.ed.ac.uk
  • Resubmit PDF: C434JGFSIbullFINAL/c434resubmit.pdf
• C435:Annotating Java Class Files with Virtual Registers for Performance
  • Abstract: The Java .class file is a compact encoding of programs for a stack-based virtual machine. It is intended for use in a networked environment, which re-quires machine independence and minimized consumption of network bandwidth. However, as in all interpreted virtual machines, performance does not match that of code generated for the target machine. We propose verifiable, machine-independent annotations to the Java class file to bring the quality of the code generated by a “just-in-time” compiler closer to that of an optimizing compiler without a sig-nificant increase in code generation time. This division of labor has expensive machine-independent analysis performed off-line and inexpensive machine-dependent code-generation performed on the client. We call this phenomenon “super-linear analysis and linear exploitation.” These annotations were designed mindful of the concurrency features of the Java language. In this paper we report results from our a machine-independent, prioritized register assignment. We also discuss other possible annotations.
  • Joel Jones and Samuel Kamin
  • Department of Computer Science University of Illinois at Urbana-Champaign
  • jjones@uiuc.edu
  • Resubmit PDF: C435JGFSIjonesFINAL/c435resubmit.pdf
• C436:Javia: A Java Interface to the Virtual Interface Architecture
  • Abstract: The Virtual Interface (VI) architecture has become the industry standard for user-level network interfaces. This paper presents the implementation and evaluation of Javia, a Java interface to the VI architecture. Javia explores two points in the design space. The first approach manages buffers in C and requires data copies between the Java heap and native buffers. The second approach relies on a Java-level buffer abstraction that eliminates the copies in the first approach. Javia achieves an effective bandwidth of 80Mbytes/sec for 8Kbyte messages, which is within 1% of those achieved by C programs. Performance evaluations of parallel matrix multiplication and of the active messages communication protocol show that Javia can serve as an efficient building block for Java cluster applications.
  • Chi-Chao Chang and Thorsten von Eicken
  • Department of Computer Science Cornell University
  • {chichao,tve}@cs.cornell.edu
  • Resubmit PDF: C436JGFSIchangFINAL/c436newchang.pdf
• C439:Extending Java Virtual Machine with Integer-Reference Conversion
  • Abstract: Java virtual machine (JVM) is an architecture-independent code ex- ecution environment. It is recently used not only for Java language but also for other languages such as Scheme and ML. On JVM, however, all values are statically-typed as either immediate or reference, and types are checked before the execution of a program to prove that invalid memory access will never occur. This property sometimes makes implementation of other languages on JVM inecient. In particular, implementation of dynamically-typed language is very inecient because all possible values including frequently-used ones such as integers must be represented by instances of a class. In this paper, we introduce a new type into JVM, which is a super- type of reference types and a tagged integer type. This allows a more efficient implementation of dynamically-typed language on JVM. It does not require any new instruction, maintains binary-compatibility of exist- ing bytecode, and retains the safety of the original JVM. We modied an existing Scheme system running on JVM to exploit this extension and got factor of 20 speedup for simple integer functions. Our extension imposes little performance penalty on existing JVM code generated from Java; we observed essentially no penalty for Spec JVM benchmarks.
  • Yutaka Oiwa, Kenjiro Taura, Akinori Yonezawa
  • University of Tokyo
  • oiwa@is.s.u-tokyo.ac.jp
  • Resubmit PDF: C439JGFSIoiwaFINAL/c439resubmitjournal.pdf
• C440:An Annotation-aware JVM Implementation
  • Abstract: The Java Bytecode language lacks expressiveness for traditional compiler optimizations, making this portable, secure software distribution format inecient as a program representation for high performance. This ineciency results from the underlying stack model, as well as the fact that many bytecode oper- ations intrinsically include sub-operations (e.g., iaload includes the address computation, array bounds checks and the actual load of the array element). The stack model, with no operand registers and limiting access to the top of the stack, prevents the reuse of values and bytecode reordering. In addition, the bytecodes have no mechanism to indicate which sub-operations in the bytecode stream are redundant or subsumed by previous ones. As a consequence, the Java Bytecode language inhibits the expression of important compiler optimizations, including common sub-expression elimination, register allocation and instruction scheduling. The bytecode stream generated by the Java front-end is a signicantly under-optimized program representation. The most common solution to overcome this aspect of the language is the use of a Just- in-Time (JIT) compiler to not only generate native code, but perform optimization as well. However, the latter is a time consuming operation in an already time-constrained translation process. In this paper we present an alternative to an optimizing JIT compiler that makes use of code annotations generated by the Java front-end. These annotations carry information concerning compiler optimization. During the translation process, an annotation-aware JVM system then uses this information to produce high- performance native code without performing much of the necessary analyses or transformations. We describe the implementation of our rst prototype of an annotation-aware JVM system consisting of a JIT compilation system. We also discuss basic ideas on how to verify annotated class les. We conclude the paper showing performance results comparing our system with other Java Virtual Machines (JVMs) running on SPARC architecture.
  • Ana Azevedo, Alex Nicolau ,Joe Hummel
  • University of California, Irvine University of Illinois, Chicago
  • aazevedo, nicolau@ics.uci.edu
  • jhummel@eecs.uic.edu
  • Resubmit PDF: C440JGFSIazevedoFINAL/c440resubmit.pdf
• C441:Design of the Kan Distributed Object System
  • Abstract: Distributed software problems are often addressed with object-oriented solutions. Objects provide the benefits of encapsulation and abstraction that have proven useful in managing the complexity of sequential code. However, the management of distributed objects is typically by means of complex APIs, such as CORBA or DCOM. The complexity of the APIs is itself a hurdle to the writing of efficient, robust programs. An alternate approach is to provide the programmer with a simple interface to an underlying object management layer that provides efficient access to objects, reliability, and sufficient power for common distributed programming tasks. We have implemented such a system, called Kan. It has a clear, simple object model with powerful semantics, embodying such concepts as atomic transactions, asynchronous method calls, and multithreading. The model constructs help the programmer avoid common concurrent programming errors, allowing clean expressions of concurrent algorithms. We describe the implemen-tation, and investigate several runtime optimizations that make performance efficient for some classes of applications. These optimizations concentrate on reducing method invocation costs. Local method invocations are optimized with a thread pool, thread inlining, and pointer swizzling. Remote method invocations are optimized with object management routines that adapt to access patterns.
  • Jerry James and Ambuj Singh
  • Department of Computer Science University of California at Santa Barbara Santa Barbara, California
  • james@eecs.ukans.edu (email changed from UCSB)
  • Resubmit PDF: C441JGFSIjamesFINAL/c441resubmit.pdf
• C442:The Java Memory Model is Fatally Flawed
  • Abstract: The Java memory model described in Chapter 17 of the Java Language Specification gives constraints on how threads interact through memory. This chapter is hard to interpret and poorly understood; it imposes constraints that prohibit common compiler optimizations and are expensive to implement on existing hardware. Most JVMs violate the constraints of the existing Java memory model; conforming to the existing specification would impose significant performance penalties. In addition, programming idioms used by some programmers and used within Sun's Java Development Kit is not guaranteed to be valid according the existing Java memory model. Furthermore, implementing Java on a shared memory multiprocessor that implements a weak memory model poses some implementation challenges not previously considered.
  • William Pugh
  • Dept. of Computer Science Univ. of Maryland, College Park
  • pugh@cs.umd.edu
  • Resubmit PDF: C442JGFSIpughFINAL/c442resubmit.pdf
• C443:Javelin++: Scalability Issues in Global Computing
  • Abstract: Javelin is a Java-based infrastructure for global computing. This paper presents Javelin++, an extension of Javelin, intended to support a much larger set of computational hosts. First, Javelin++'s switch from Java applets to Java applications is explained. Then, two scheduling schemes are presented: probabilistic work stealing and deterministic work stealing. The distributed deterministic work stealing is integrated with a distributed deterministic eager scheduler. An additional fault tolerance mechanism is implemented for replacing hosts that have failed or retreated. A Javelin++ API is sketched, then illustrated on a raytracing application. Performance results for the two schedulers are reported, indicating that Javelin++, with its broker network, scales better than the original Javelin.
  • Michael O. Neary, Sean P. Brydon, Paul Kmiec, Sami Rollins, Peter Cappello,
  • Department of Computer Science University of California, Santa Barbara Santa Barbara, CA 93106
  • {neary, brydon, virus, srollins, cappello}@cs.ucsb.edu
  • Resubmit PDF: C443JGFSInearyFINAL/c443topresubmit.pdf
• C444:Design, Implementation, and Evaluation of Optimizations in a Java™ Just-In-Time Compiler
  • Abstract:The Java language incurs a runtime overhead for exception checks and object accesses, which are executed without an interior pointer in order to ensure safety. It also requires type inclusion test, dynamic class loading, and dynamic method calls in order to ensure flexibility. A “Just-In-Time” (JIT) compiler generates native code from Java byte code at runtime. It must improve the run-time performance without compromising the safety and flexibility of the Java language. We designed and implemented effective optimizations for a JIT compiler, such as exception check elimination, common subexpression elimination, simple type inclusion test, method inlining, and devirtualization of dynamic method call. We evaluate the performance benefits of these optimizations based on various statistics collected using SPECjvm98, its candidates, and two JavaSoft applications with byte code sizes ranging from 23000 to 280000 bytes. Each optimization contributes to an improvement in the performance of the programs.
  • Kazuaki Ishizaki, Motohiro Kawahito, Toshiaki Yasue, Mikio Takeuchi, Takeshi Ogasawara, Toshio Suganuma, Tamiya Onodera, Hideaki Komatsu, and Toshio Nakatani
  • IBM Tokyo Research Laboratory 1623-14, Shimotsuruma, Yamato, Kanagawa, 242-8502, Japan
  • ishizaki@trl.ibm.co.jp
  • Resubmit PDF: C444JGFSIishizakiFINAL/C444newishizaki-2nd.pdf
• C445:Complex numbers for Java
  • Abstract:Efficient and elegant complex numbers are one of the preconditions for the use of Java in scientific computing. This paper introduces a preprocessor and its translation rules that map a new basic type complex and its operations to pure Java. For the mapping is insufficient to just replace one complex-variable with two double-variables. Compared to code that uses Complex objects and method invocations to express arithmetic operations the new basic type increases readability and it is also executed faster. On average, the versions of our benchmark programs that use the basic type outperform the class-based versions by a factor of 2 up to 21 (depending on the JVM used).
  • Michael Philippsen and Edwin Günthner
  • University of Karlsruhe
  • phlipp@ira.uka.de
  • http://wwwipd.ira.uka.de/JavaParty/
  • Resubmit PDF: C445JGFSIcomplexphilippsenFINAL/resubmitC445/complexe.pdf
• C457:Cooperating distributed garbage collectors for Clusters and beyond
  • Abstract:The contribution of this paper is twofold. First a distributed garbage collector (DGC) is presented that is optimized for remote method invocation in reliable networks, such as cur-rent clusters of workstations. Since the algorithm does not require extra acknowledgement messages, even while col-lecting, it does not increase the latency of a remote call. Then it is discussed how several DGCs can cooperate in networks that consist of different areas with respect to communication, i.e., of areas with different reliability prop-erties. Proper placement and use of bridge objects allow to select an optimized DGC for every area.
  • Michael Philippsen
  • University of Karlsruhe
  • phlipp@ira.uka.de
  • Resubmit PDF:C457JGFSIgarbagephillippsenFINAL/dgc.pdf