Taming Multi-core Parallelism with Concurrent Mixin Layers

The recent shift in computer system design to multi-core technology requires that the developer leverage explicit parallel programming techniques in order to utilize available performance. Nevertheless, developing the requisite parallel applications remains a prohibitively-difficult undertaking, particularly for the general programmer. To mitigate many of the challenges in creating concurrent software, this paper introduces a new parallel programming methodology that leverages feature-oriented programming (FOP) to logically decompose a product line architecture (PLA) into concurrent execution units. In addition, our efficient implementation of this methodology, that we call concurrent mixin layers, uses a layered architecture to facilitate the development of parallel applications. To validate our methodology and accompanying implementation, we present a case study of a product line of multimedia applications deployed within a typical multi-core environment. Our performance results demonstrate that a product line can be effectively transformed into parallel applications capable of utilizing multiple cores, thus improving performance. Furthermore, concurrent mixin layers significantly reduces the complexity of parallel programming by eliminating the need for the programmer to introduce explicit low-level concurrency control. Our initial experience gives us reason to believe that concurrent mixin layers is a promising technique for taming parallelism in multi-core environments

Architectural Refactoring for Fast and Modular Bioinformatics Sequence Search

Bioinformaticists use the Basic Local Alignment Search Tool (BLAST) to characterize an unknown sequence by comparing it against a database of known sequences, thus detecting evolutionary relationships and biological properties. mpiBLAST is a widely-used, high-performance, open-source parallelization of BLAST that runs on a computer cluster delivering super-linear speedups. However, the Achilles heel of mpiBLAST is its lack of modularity, adversely affecting maintainability and extensibility; an effective architectural refactoring will benefit both users and developers. This paper describes our experiences in the architectural refactoring of mpiBLAST into a modular, high-performance software package. Our evaluation of five component-oriented designs culminated in a design that enables modularity while retaining high-performance. Furthermore, we achieved this refactoring effectively and efficiently using eXtreme Programming techniques. These experiences will be of value to software engineers faced with the challenge of creating maintainable and extensible, high-performance, bioinformatics software

Towards Object-Oriented Klaim

Abstract By its own nature, mobile code requires flexibility in order to be adaptive to any execution context it may be run in. In this paper we investigate this flexibility requirement from the design point of view, and propose a solution based on the mixin technique to fulfill it. We also propose an extension of the language K laim with object-oriented features, as an application of this approach

ContextErlang: A language for distributed context-aware self-adaptive applications

Self-adaptive software modifies its behavior at run time to satisfy changing requirements in a dynamic environment. Context-oriented programming (COP) has been recently proposed as a specialized programming paradigm for context-aware and adaptive systems. COP mostly focuses on run time adaptation of the application’s behavior by supporting modular descriptions of behavioral variations. However, self-adaptive applications must satisfy additional requirements, such as distribution and concurrency, support for unforeseen changes and enforcement of correct behavior in the presence of dynamic change. Addressing these issues at the language level requires a holistic design that covers all aspects and takes into account the possibly cumbersome interaction of those features, for example concurrency and dynamic change. We present ContextErlang, a COP programming language in which adaptive abstractions are seamlessly integrated with distribution and concurrency. We define ContextErlang’s formal semantics, validated through an executable prototype, and we show how it supports formal proofs that the language design ensures satisfaction of certain safety requirements. We provide empirical evidence that ContextErlang is an effective solution through case studies and a performance assessment. We also show how the same design principles that lead to the development of ContextErlang can be followed to systematically design contextual extensions of other languages. A concrete example is presented concerning ContextScala

Integrating independent components with on-demand remodularization

This paper proposes language concepts that facilitate the separation of an application into independent reusable building blocks and the integration of pre-build generic software components into applications that have been developed by third party vendors. A key element of our approach are on-demand remodularizations, meaning that the abstractions and vocabulary of an existing code base are translated into the vocabulary understood by a set of components that are connected by a common collaboration interface. This general concept allows us to mix-and-match remodularizations and components on demand

Context-Oriented Image Processing: Reconciling genericity and performance through contexts

International audienceGenericity aims at providing a very high level of abstraction in order, for instance, to separate the general shape of an algorithm from specific implementation details. Reaching a high level of genericity through regular object-oriented techniques has two major drawbacks, however: code cluttering (e.g. class / method proliferation) and performance degradation (e.g. dynamic dispatch). In this paper, we explore a potential use for the Context-Oriented programming paradigm in order to maintain a high level of genericity in an experimental image processing library, without sacrificing either the performance or the original object-oriented design of the application

Classbox/J: Controlling the Scope of Change in Java

International audienceUnanticipated changes to complex software systems can introduce anomalies such as duplicated code, suboptimal inheritance rela- tionships and a proliferation of run-time downcasts. Refactoring to eliminate these anomalies may not be an option, at least in certain stages of software evolution. Classboxes are modules that restrict the visibility of changes to selected clients only, thereby offering more freedom in the way unanticipated changes may be imple- mented, and thus reducing the need for convoluted design anoma- lies. In this paper we demonstrate how classboxes can be imple- mented in statically-typed languages like Java. We also present an extended case study of Swing, a Java GUI package built on top of AWT, and we document the ensuing anomalies that Swing intro- duces. We show how Classbox/J, a prototype implementation of classboxes for Java, is used to provide a cleaner implementation of Swing using local refinement rather than subclassing