Paul A. Gray

Harness: a next generation distributed virtual machine

Abstract Heterogeneous Adaptable Reconfigurable Networked SystemS (HARNESS) is an experimental metacomputing system [L. Smarr, C.E. Catlett, Communications of the ACM 35 (6) (1992) 45–52] built around the services of a highly customizable and reconfigurable Distributed Virtual Machine (DVM). The successful experience of the HARNESS design team with the Parallel Virtual Machine (PVM) project has taught us both the features which make the DVM model so valuable to parallel programmers and the limitations imposed by the PVM design. HARNESS seeks to remove some of those limitations by taking a totally different approach to creating and modifying a DVM.

MPI and Java-MPI: Contrasts and Comparisons of Low-Level Communication Performance

Java is receiving increasing attention as the most popular platform for distributed and collaborative computing. However, it is still subject to significant performance drawbacks in comparison to other programming languages such as C and Fortran. This paper represents the current status of our ongoing project which intends to conduct a detailed experimental evaluation on the suitability of Java in these environments, with particular focus on its message-passing performance for one-to-one as well as one-to-many and many-to- many data exchange patterns. We also emphasize both methodology and evaluation guidelines in order to ensure reproducibility, sound interpretation, and comparative analysis of performance results. Some of the important parameters which characterize the communication performance of MPI and Java-MPI such as latency, asymptotic bandwidth and N-half are investigated. In addition, we introduce two different types of pipeline effects - intra-message and inter-message - that have significant influence on the message-passing performance. For this purpose we have developed a low-level message-passing benchmark suite, which we have used to evaluate and compare different message-passing environments on the IBM SP-2.

Multi-language programming environments for high performance Java computing

Recent developments in processor capabilities, software tools, programming languages and programming paradigms have brought about new approaches to high performance computing. A steadfast component of this dynamic evolution has been the scientific community’s reliance on established scientific packages. As a consequence, programmers of high-performance applications are reluctant to embrace evolving languages such as Java. This paper describes the Java-to-C Interface (JCI) tool which provides application programmers wishing to use Java with immediate accessibility to existing scientific packages. The JCI tool also facilitates rapid development and reuse of existing code. These benefits are provided at minimal cost to the programmer. While beneficial to the programmer, the additional advantages of mixed-language programming in terms of application performance and portability are addressed in detail within the context of this paper. In addition, we discuss how the JCI tool is complementing other ongoing projects such as IBM’s High-Performance Compiler for Java (HPCJ) and IceT’s metacomputing environment.

CCF: Collaborative Computing Frameworks

CCF (Collaborative Computing Frameworks) is a suite of software systems, communications protocols, and tools that enable collaborative, computer-based cooperative work. CCF constructs a virtual work environment on multiple computer systems connected over the Internet, to form a Collaboratory. In this setting, participants interact with each other, simultaneously access and operate computer applications, refer to global data repositories or archives, collectively create and manipulate documents or other artifacts, perform computational transformations, and conduct a number of other activities via telepresence. Research issues addressed in this project include problem solving environments and methodologies for laboratory and instrument-based scientific disciplines, and computer science issues in heterogeneous distributed systems. New approaches are being investigated and developed for fast multiway communication, robust geographically distributed data management methodologies, high-performance computational transforms inlined within collaboration sessions, and related auxiliary issues such as active documents, security, archival storage, and experiment management and control. In this paper, we discuss the design philosophy and systems rationale behind CCF, describe the major subsystems of the collaborative computing environment, and discuss the salient features of the system.

Native‐language‐based distributed computing across network and filesystem boundaries

This paper discusses how the aspects unique to the Java programming language can be combined with complementary and unique aspects of other languages such as C and Fortran. This combining of the strong features of Java, such as portability and platform independence, with packages and legacy codes written in traditional languages such as C and Fortran results in a program blend which exhibits portability and speed not realizable by any of these languages individually. One area where this confluence of previously disparate language features has strong potential is in the area of distributed, concurrent computing over heterogeneous platforms and across local network and filesystem boundaries – the setting addressed within this paper. Also addressed in this paper are the pivotal aspects of the Java bytecode representation of a class object which makes the porting of shared libraries across network boundaries, filesystems, and architectures possible.

Metacomputing with the ICET System

IceT is based on the premise that distributed computations involve resources, processes, data, and users, and that secure yet flexible mechanisms for cooperation and communication between these types of entities is the key to metacomputing infrastructures. The basis for IceT computing is process-oriented distributed memory multicomputing, but with key differences, including merging and splitting of virtual machines and code and data mobility. This paper describes the design philosophy of IceT and reports on qualitative experiences with preliminary use of a prototype system.

The IceT Environment for Parallel and Distributed Computing

The current programming models, tools and environments associated with Internet programming and parallel, high-performance distributed computing have remained isolated from one another. The focus of the IceT project has been to bring together the common and unique attributes of these areas. The result is a confluence of technologies in a parallel programming environment with several novel characteristics. The result provides users with a parallel, multi-user, distributed programming environment; upon which processes and data are allowed to migrate and to be transfered throughout owned and unowned resources, under security measures imposed by owners of the local resources.

Numerical Algorithms of the Lawrence--Doniach Model for Layered Superconductors and their Parallel Implementation

The Lawrence--Doniach model is often used for studying vortex dynamics in superconductors which exhibit a layered structure. In solving these model equations numerically, the added degrees of complexity due to the coupling and nonlinearity of the model often warrant the extensive use of high-performance computers for their solution. Approaches for reducing the complexity of the Lawrence--Doniach model and for simplifying the calculation of the numerical solution are presented in this work. Numerical results and benchmarks are included for models involving the motion of vortices due to an applied current and the pinning of vortices due to nonuniform pinning sites (normal inclusions) placed within the material.

Developing technologies for broad-network concurrent computing

Abstract Recent developments in networking infrastructures, computer workstation capabilities, software tools, and programming languages have motivated new approaches to broad-network concurrent computing. This paper describes extensions to concurrent computing which blend new and evolving technologies to extend users access to resources beyond their local network. The result is a concurrent programming environment which can dynamically extend over network and file system boundaries to envelope additional resources, to enable multiple-user collaborative programming, and to achieve a more optimal process mapping. Additional aspects of the derivative environment feature extended portability and support for the accessing of legacy codes and packages. This paper describes the advantages of such a design and how they have been implemented in the environment termed “IceT”.

Advances in Heterogeneous Network Computing

Frameworks that facilitate network computing have proven viable for high performance applications as well as for traditional distributed computing. Performance and functionality that such methodologies can provide, as well as their limitations and potential, have become reasonably well understood. In this paper, we discuss some selected aspects of heterogeneous computing in the context of the PVM system, and describe evolutionary enhancements to the system. Our experiences with PVM and experiments with optimization, light-weight processes, and client-server computing, have suggested useful directions that the next generation of heterogeneous systems might follow. A prototype design of such a next-generation heterogeneous computing framework is presented in the second half of this paper.