Fortran M is a small set of extensions to Fortran 77 that supports a modular approach to the design of message-passing programs. It has the following features. (1) Modularity. Programs are constructed by using explicitly-declared communication channels to plug together program modules called processes. A process can encapsulate common data, subprocesses, and internal communication. (2) Safety. Operations on channels are restricted so as to guarantee deterministic execution, even in dynamic computations that create and delete processes and channels. Channels are typed, so a compiler can check for correct usage. (3) Architecture Independence. The mapping of processes to processors can be specified with respect to a virtual computer with size and shape different from that of the target computer. Mapping is specified by annotations that influence performance but not correctness. (4) Efficiency. Fortran M can be compiled efficiently for uniprocessors, sharedmemory computers, distributed-m...

CC++ is Compositional C++ , a parallel object-oriented notation that consists of C++ with six extensions. The goals of the CC++ project are to provide a theory, notation and tools for developing reliable scalable concurrent program libraries, and to provide a framework for unifying: 1. distributed reactive systems, batch-oriented numeric and symbolic applications, and user-interface systems, 2. declarative programs and object-oriented imperative programs, and 3. deterministic and nondeterministic programs. This paper is a brief description of the motivation for CC++ , the extensions to C++ , a few examples of CC++ programs with reasoning about their correctness, and an evaluation of CC++ in the context of other research on concurrent computation. A short description of C++ is provided.

This dissertation shows a new approach to writing object-oriented parallel programs based on design patterns, frameworks, and multiple layers of abstraction.

We describe the PCN programming system, focusing on those features designed to improve the productivity of scientists and engineers using parallel supercomputers. These features include a simple notation for the concise specification of concurrent algorithms, the ability to incorporate existing Fortran and C code into parallel applications, facilities for reusing parallel program components, a portable toolkit that allows applications to be developed on a workstation or small parallel computer and run unchanged on supercomputers, and integrated debugging and performance analysis tools. We survey representative scientific applications and identify problem classes for which PCN has proved particularly useful. Keywords: PCN, program composition, parallel programming, reuse, templates. 1 Introduction After many years as academic curiosities, computers combining hundreds or thousands of powerful microprocessors have overtaken vector processors and become essential tools for scientists and...

We present an overview of research at the CRPC designed to provide an efficient, portable programming model for scientific applications possessing both task and data parallelism. Fortran M programs exploit task parallelism by providing language extensions for user-defined process management and typed communication channels. A combination of compiler and run-time system support ensures modularity, safety, portability, and efficiency. Fortran D and High Performance Fortran programs exploit data parallelism by providing language extensions for user-defined data decomposition specifications, parallel loops, and parallel array operations. Compile-time analysis and optimization yield efficient, portable programs. We design an interface for using a task-parallel language to coordinate concurrent data-parallel computations. The interface permits concurrently executing data-parallel computations to interact through messages. A key notion underlying the proposed interface is the integration of F...

this paper, we discuss alternative approaches to the realization of this principle, which holds that properties of program components should be preserved when those components are composed in parallel with other program components. We review two programming languages, Strand and Program Composition Notation, that support compositionality via a small number of simple concepts, namely monotone operations on shared objects, a uniform addressing mechanism, and parallel composition. Both languages have been used extensively for large-scale application development, allowing us to provide an informed assessment of their strengths and weaknesses. We observe that while compositionality simplifies development of complex applications, the use of specialized languages hinders reuse of existing code and tools, and the specification of domain decomposition strategies. This suggests an alternative approach based on small extensions to existing sequential languages. We conclude the paper with a discussion of two languages that realize this strategy. Categories and Subject Descriptors: D.3.2 [Programming Languages]: Language Classifications ---Concurrent, distributed, and parallel languages; D.3.3 [Programming Languages]: Language Constructs and Features---Concurrent programming structures General Terms: Languages Additional Key Words and Phrases: Compositionality, Parallel Languages, Parallel Programming ACM Transactions on Programming Languages and Systems, Vol. 8, No. 1, January 1999. Compositional Parallel Programming Languages \Delta 113 1. INTRODUCTION Parallel programming is widely regarded as difficult: more difficult than sequential programming, and perhaps (at least this is our view) more difficult than it needs to be. In addition to the normal programming concerns, the para...

We consider a system with the infrastructure for the creation and interconnection of large numbers of distributed persistent objects. This system is exemplified by the Internet: potentially, every appliance and document on the Internet has both persistent state and the ability to interact with large numbers of other appliances and documents on the Internet. This paper elucidates the characteristics of such a system, and proposes the compositional requirements of its corresponding infrastructure. We explore the problems of specifying, composing, reasoning about, and implementing applications in such a system. A specific concern of our research is developing the infrastructure to support structuring distributed applications by using sequential, choice, and parallel composition, in the anarchic environment where application compositions may be unforeseeable, and interactions may be unknown prior to actually occurring. The structuring concepts discussed are relevant to a wide range of dist...

We investigate the performance of wormhole-routed networks under hybrid traffic loads to examine the impact of long and short messages on each other. The short messages not only experience increased average latency but also experience a large increase in the variance of that latency. The negative performance impact of long messages increases proportionally with both the fraction and size of the long messages. We also explore two techniques: virtual lanes and adaptive routing to improve network performance under the hybrid traffic loads. Performance losses due to long messages can be dramatically reduced with either technique. The two techniques are complementary, so employing them simultaneously yields the best performance of all, virtually eliminating performance losses experienced by short messages. This means that packetization may not be necessary in such networks.

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Object-oriented programming, design patterns, and frameworks are common techniques that have been used to reduce the complexity of sequential programming. We have applied these techniques to the more difficult domain of parallel programming. This paper describes CO 2P 3S, a pattern-based parallel programming system that generates parallel programs from parallel design patterns. We demonstrate CO 2P 3S by applying a new design pattern called the Wavefront pattern to three problems. We show that it is quick and easy to use CO 2P 3S to generate structurally correct parallel programs with good speed-ups on shared-memory computers. 1.