Reusable aspect-oriented implementations of concurrency patterns and mechanisms

In this paper, we present a collection of well-known high-level concurrency patterns and mechanisms, coded in AspectJ. We discuss benefits of these implementations relative to plain Java implementations of the same concerns. We detect benefits from using AspectJ in all the cases presented, in the form of higher modularity, reuse, understandability and unpluggability. For most of the implementations, two alternatives can be used: one based on traditional pointcut interfaces and one based on annotations.Fundo Europeu de Desenvolvimento Regional (FEDER).Fundação para a Ciência e a Tecnologia (FCT) - PPC-VM Project POSI/CHS/47158/2002; Project SOFTAS (POSI/EIA/60189/2004)

Revisiting Actor Programming in C++

The actor model of computation has gained significant popularity over the last decade. Its high level of abstraction makes it appealing for concurrent applications in parallel and distributed systems. However, designing a real-world actor framework that subsumes full scalability, strong reliability, and high resource efficiency requires many conceptual and algorithmic additives to the original model. In this paper, we report on designing and building CAF, the "C++ Actor Framework". CAF targets at providing a concurrent and distributed native environment for scaling up to very large, high-performance applications, and equally well down to small constrained systems. We present the key specifications and design concepts---in particular a message-transparent architecture, type-safe message interfaces, and pattern matching facilities---that make native actors a viable approach for many robust, elastic, and highly distributed developments. We demonstrate the feasibility of CAF in three scenarios: first for elastic, upscaling environments, second for including heterogeneous hardware like GPGPUs, and third for distributed runtime systems. Extensive performance evaluations indicate ideal runtime behaviour for up to 64 cores at very low memory footprint, or in the presence of GPUs. In these tests, CAF continuously outperforms the competing actor environments Erlang, Charm++, SalsaLite, Scala, ActorFoundry, and even the OpenMPI.Comment: 33 page

A Programming Model for Hybrid Workflows: combining Task-based Workflows and Dataflows all-in-one

This paper tries to reduce the effort of learning, deploying, and integrating several frameworks for the development of e-Science applications that combine simulations with High-Performance Data Analytics (HPDA). We propose a way to extend task-based management systems to support continuous input and output data to enable the combination of task-based workflows and dataflows (Hybrid Workflows from now on) using a single programming model. Hence, developers can build complex Data Science workflows with different approaches depending on the requirements. To illustrate the capabilities of Hybrid Workflows, we have built a Distributed Stream Library and a fully functional prototype extending COMPSs, a mature, general-purpose, task-based, parallel programming model. The library can be easily integrated with existing task-based frameworks to provide support for dataflows. Also, it provides a homogeneous, generic, and simple representation of object and file streams in both Java and Python; enabling complex workflows to handle any data type without dealing directly with the streaming back-end.Comment: Accepted in Future Generation Computer Systems (FGCS). Licensed under CC-BY-NC-N

Television and the popular: viewing from the British perspective

The academic discipline of television studies has been constituted by the claim that television is worth studying because it is popular. Yet this claim has also entailed a need to defend the subject against the triviality that is associated with the television medium because of its very popularity. This article analyses the many attempts in the later twentieth and twenty-first centuries to constitute critical discourses about television as a popular medium. It focuses on how the theoretical currents of Television Studies emerged and changed in the UK, where a disciplinary identity for the subject was founded by borrowing from related disciplines, yet argued for the specificity of the medium as an object of criticism. Eschewing technological determinism, moral pathologization and sterile debates about television's supposed effects, UK writers such as Raymond Williams addressed television as an aspect of culture. Television theory in Britain has been part of, and also separate from, the disciplinary fields of media theory, literary theory and film theory. It has focused its attention on institutions, audio-visual texts, genres, authors and viewers according to the ways that research problems and theoretical inadequacies have emerged over time. But a consistent feature has been the problem of moving from a descriptive discourse to an analytical and evaluative one, and from studies of specific texts, moments and locations of television to larger theories. By discussing some historically significant critical work about television, the article considers how academic work has constructed relationships between the different kinds of objects of study. The article argues that a fundamental tension between descriptive and politically activist discourses has confused academic writing about ›the popular‹. Television study in Britain arose not to supply graduate professionals to the television industry, nor to perfect the instrumental techniques of allied sectors such as advertising and marketing, but to analyse and critique the medium's aesthetic forms and to evaluate its role in culture. Since television cannot be made by ›the people‹, the empowerment that discourses of television theory and analysis aimed for was focused on disseminating the tools for critique. Recent developments in factual entertainment television (in Britain and elsewhere) have greatly increased the visibility of ›the people‹ in programmes, notably in docusoaps, game shows and other participative formats. This has led to renewed debates about whether such ›popular‹ programmes appropriately represent ›the people‹ and how factual entertainment that is often despised relates to genres hitherto considered to be of high quality, such as scripted drama and socially-engaged documentary television. A further aspect of this problem of evaluation is how television globalisation has been addressed, and the example that the issue has crystallised around most is the reality TV contest Big Brother. Television theory has been largely based on studying the texts, institutions and audiences of television in the Anglophone world, and thus in specific geographical contexts. The transnational contexts of popular television have been addressed as spaces of contestation, for example between Americanisation and national or regional identities. Commentators have been ambivalent about whether the discipline's role is to celebrate or critique television, and whether to do so within a national, regional or global context. In the discourses of the television industry, ›popular television‹ is a quantitative and comparative measure, and because of the overlap between the programming with the largest audiences and the scheduling of established programme types at the times of day when the largest audiences are available, it has a strong relationship with genre. The measurement of audiences and the design of schedules are carried out in predominantly national contexts, but the article refers to programmes like Big Brother that have been broadcast transnationally, and programmes that have been extensively exported, to consider in what ways they too might be called popular. Strands of work in television studies have at different times attempted to diagnose what is at stake in the most popular programme types, such as reality TV, situation comedy and drama series. This has centred on questions of how aesthetic quality might be discriminated in television programmes, and how quality relates to popularity. The interaction of the designations ›popular‹ and ›quality‹ is exemplified in the ways that critical discourse has addressed US drama series that have been widely exported around the world, and the article shows how the two critical terms are both distinct and interrelated. In this context and in the article as a whole, the aim is not to arrive at a definitive meaning for ›the popular‹ inasmuch as it designates programmes or indeed the medium of television itself. Instead the aim is to show how, in historically and geographically contingent ways, these terms and ideas have been dynamically adopted and contested in order to address a multiple and changing object of analysis

Getting It Right: Strategies for After-School Success

This report synthesizes the last 10 years of findings from P/PV's and other researchers' work to address one of the most demanding challenges facing today's after-school programs -- how to create and manage programs that stand the best chance of producing specific, policy-relevant outcomes. It examines recruitment strategies that attract young people to activities, the qualities that make activities engaging and motivate participants to attend regularly, and the infrastructure -- staffing, management and monitoring -- needed to support such activities. The report's final chapter explores the fiscal realities of after-school programming, considering how administrators might stretch existing dollars to enhance services

COMPROF and COMPLACE : shared-memory communication profiling and automated thread placement via dynamic binary instrumentation

Funding: This work was generously supported by UK EPSRC Energise, grant number EP/V006290/1.This paper presents COMPROF and COMPLACE, a novel profiling tool and thread placement technique for shared-memory architectures that requires no recompilation or user intervention. We use dynamic binary instrumentation to intercept memory operations and estimate inter-thread communication overhead, deriving (and possibly visualising) a communication graph of data-sharing between threads. We then use this graph to map threads to cores in order to optimise memory traffic through the memory system. Different paths through a system's memory hierarchy have different latency, throughput and energy properties, COMPLACE exploits this heterogeneity to provide automatic performance and energy improvements for multi-threaded programs. We demonstrate COMPLACE on the NAS Parallel Benchmark (NPB) suite where, using our technique, we are able to achieve improvements of up to 12% in the execution time and up to 10% in the energy consumption (compared to default Linux scheduling) while not requiring any modification or recompilation of the application code.Postprin