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Improving responsiveness of time-sensitive applications by exploiting dynamic task dependencies

SOFTWARE-PRACTICE & EXPERIENCE 2018年第4期48卷 820-841页

作者： Cucinotta, Tommaso Abeni, Luca Lelli, Juri Lipari, Giuseppe Scuola Super Sant Anna ReTiS Lab Via G Moruzzi 1 I-56124 Pisa Italy ARM Ltd Cambridge CB1 9NJ England Univ Lille CNRS UMR 9189 CRIStAL F-59800 Lille France

In this paper, a mechanism is presented for reducing priority inversion in multiprogrammed computing systems. Contrary to well-known approaches from the literature, this paper tackles cases where the dependency relationships among tasks cannot be known in advance to the operating system. The presented mechanism allows tasks to explicitly declare aforementioned relationships, enabling the operating system scheduler to take advantage of such information and trigger priority inheritance, resulting in reduced priority inversion. We present the prototype implementation of the concept within the Linux kernel in the form of modifications to the standard Portable Operating System Interface (POSIX) condition variable code, along with an extensive evaluation, including a quantitative assessment of the benefits for applications making use of the technique and comprehensive overhead measurements. In addition, we present an associated technique for the theoretical schedulability analysis of a system using the new mechanism, which is useful to determine whether all tasks can meet their deadlines or not, in the specific scenario of tasks interacting only through remote procedure calls and under partitioned scheduling.

关键词： concurrent programming priority inheritance priority inversion real-time analysis real-time scheduling on Linux

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Towards a specification of the ToonTalk language

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JOURNAL OF VISUAL LANGUAGES AND COMPUTING 2008年第5期19卷 574-597页

作者： Morgado, Leonel Kahn, Ken UTAD Univ Tras Os Montes & Alto Doura GECAD Grp Invest Engn Conhecimento & Apoio Decisa Vila Real Portugal Animated Programs Oxford England

ToonTalk is a child-oriented programming language whose environment is an animated virtual world, with objects that children can pick up and use as in a game, such as birds, trucks, and robots, providing direct child-oriented metaphors for programming constructs. Actions performed by a programmer's avatar with these objects are both code and coding. ToonTalk is a powerful system, not just a "toy" system: it is based upon concurrent constraint programming languages, and programs written in languages such as Flat Guarded Horn Clauses and Flat concurrent Prolog can be straightforwardly constructed in ToonTalk. However, there is not a specification of ToonTalk, for ready implementation in other environments. We propose that the ToonTalk language lies not in the animations displayed by the current environment, but on the actions performed by the programmer with virtual world objects;we present a description and analysis of the methods the ToonTalk language provides to programmers for expressing programs. (C) 2007 Elsevier Ltd. All rights reserved.

关键词： ToonTalk animated programming action-based programming children programming concurrent programming virtual environments virtual worlds virtual environment

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Modular Checkpointing for Atomicity

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ELECTRONIC NOTES IN THEORETICAL COMPUTER SCIENCE 2007年第9期174卷 85-115页

作者： Ziarek, Lukasz Schatz, Philip Jagannathan, Suresh Purdue Univ Dept Comp Sci W Lafayette IN 47907 USA

Transient faults that arise in large-scale software systems can often be repaired by re-executing the code in which they occur. Ascribing a meaningful semantics for safe re-execution in multi-threaded code is not obvious, however. For a thread to correctly re-execute a region of code, it must ensure that all other threads which have witnessed its unwanted effects within that region are also reverted to a meaningful earlier state. If not done properly, data inconsistencies and other undesirable behavior may result. However, automatically determining what constitutes a consistent global checkpoint is not straightforward since thread interactions are a dynamic property of the program. In this paper, we present a safe and efficient checkpointing mechanism for concurrent ML (CML) that can be used to recover fromtransient faults. We introduce a new linguistic abstraction called stabilizers that permits the specification of per-thread monitors and the restoration of globally consistent checkpoints. Global states are computed through lightweight monitoring of communication events among threads (e.g. message-passing operations or updates to shared variables). Our checkpointing abstraction provides atomicity and isolation guarantees during state restoration ensuring restored global states are safe. Our experimental results on several realistic, multithreaded, server-style CML applications, including a web server and a windowing toolkit, show that the overheads to use stabilizers are small, and lead us to conclude that they are a viable mechanism for defining safe checkpoints in concurrent functional programs. Our experiments conclude with a case study illustrating how to build open nested transactions from our checkpointing mechanism.

关键词： concurrent programming error recovery checkpointing transactions concurrent ML exception handling atomicity

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A HIERARCHICAL PROGRAM STRUCTURE FOR concurrent FAULT TOLERANT SOFTWARE

MICROPROCESSING AND MICROPROGRAMMING

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MICROPROCESSING AND MICROprogramming 1993年第1-5期37卷 179-182页

作者： CLEMATIS, A GIANUZZI, V CNR IST MATEMAT APPLI-16132 GENOAITALY UNIV GENOA DIPARTIMENTO INFORMAT & SCI INFORMAZI-16132 GENOAITALY

A new approach to software fault tolerance in concurrent programs modeled as reactive systems is proposed. It is based on a hierarchical structure and on the combined use of different fault tolerant schemes (e.g. transaction to protect data and conversation like scheme to protect processes). Among the merits of this new approach there is the possibility of an effective use of different programming languages to implement diverse software versions also in concurrent programs.

关键词： SOFTWARE FAULT TOLERANCE concurrent programming BACKWARD ERROR RECOVERY TRANSACTION BASED SYSTEMS

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Scripting Multiple CPUs with Safe Data Sharing

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IEEE SOFTWARE 2014年第5期31卷 44-51页

作者： Skyrme, Alexandre Rodriguez, Noemi Ierusalimschy, Roberto Pontifical Catholic Univ Rio de Janeiro Rio De Janeiro Brazil

Scripting languages are very popular and are being used to implement a wide range of applications. Meanwhile, multi-core processors are everywhere, from dektop computers to mobile devices, and concurrency has become the only means to improve performance. However, concurrent programming remains difficult and despite some interest in researching new concurrency models for compiled languages, the conventional concurrency support in scripting languages is still lacking. In this paper we are interested in \emphsafe data sharing for scripting languages. We explore the landscape of conventional concurrency support in popular scripting languages and discuss some of its limitations. Then, we identify some emerging concurrency patterns in scripting languages, namely: no-default sharing, data ownership, futures and data immutability. Finally, we analyze some limitations in existing mechanisms and discuss how the patterns we identified can be used to provide safe data sharing in scripting languages. [ABSTRACT FROM PUBLISHER]

关键词： concurrent computing concurrent programming data sharing Information sharing languages programming languages Message systems Multithreading programming scripting software Software development software engineering Synchronization

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On the Effectiveness of Contracts as Test Oracles in the Detection and Diagnosis of Functional Faults in concurrent Object-Oriented Software

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IEEE TRANSACTIONS ON SOFTWARE ENGINEERING 2014年第10期40卷 971-992页

作者： Araujo, Wladimir Briand, Lionel C. Labiche, Yvan Juniper Networks Sunnyvale CA 94089 USA Univ Luxembourg SnT Ctr L-1359 Luxembourg Luxembourg Carleton Univ Dept Syst & Comp Engn Ottawa ON K1S 5B6 Canada

Design by contract (DbC) is a software development methodology that focuses on clearly defining the interfaces between components to produce better quality object-oriented software. Though there exists ample support for DbC for sequential programs, applying DbC to concurrent programs presents several challenges. Using Java as the target programming language, we tackle such challenges by augmenting the Java Modelling Language (JML) and modifying the JML compiler (jmlc) to generate runtime assertion checking code to support DbC in concurrent programs. We applied our solution in a carefully designed case study on a highly concurrent industrial software system from the telecommunications domain to assess the effectiveness of contracts as test oracles in detecting and diagnosing functional faults in concurrent software. Based on these results, clear and objective requirements are defined for contracts to be effective test oracles for concurrent programs whilst balancing the effort to design them. Effort is measured indirectly through the contract complexity measure (CCM), a measure we define. Main results include that contracts of a realistic level of completeness and complexity can detect around 76 percent of faults and reduce the diagnosis effort for such faults tenfold. We, therefore, show that DbC can be applied to concurrent software and can be a valuable tool to improve the economics of software engineering.

关键词： Software/Program Verification-programming by contract Software Quality/SQA-Measurement applied to SQA and V&V concurrent programming object-oriented programming

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A concurrent van Emde Boas array as a fast and simple concurrent dynamic set alternative

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CONCURRENCY AND COMPUTATION-PRACTICE & EXPERIENCE 2014年第2期26卷 360-379页

作者： Kulakowski, Konrad AGH Univ Sci & Technol Dept Appl Comp Sci EAIiIB PL-30059 Krakow Poland

Increasing demand for computationally efficient algorithms and processors has turned the attention of researchers toward parallel and concurrent solutions. Because the frequency of contemporary processors cannot be tweaked infinitely, the only hopes for squeezing more performance from computers are parallel processing and parallel computation. The important part of every parallel solution is concurrent data structures, which allow multithread programming environments to be taken advantage of. In this article, a new concurrent dynamic set structure is proposed. It is based on the van Emde Boas trees concept, where on every node of a tree, an array of the node's children is stored. The structure is equipped with a simple but effective locking algorithm, which allows it to be used concurrently by any number of threads. The presented algorithm idea is accompanied by an experimental implementation written in JAVA 6. Preliminary tests prove that, especially for moderately larger data sets with a predominance of read operations, the concurrent van Emde Boas array proposed in this article may be a viable alternative for other structures providing a similar functionality. Copyright (c) 2013 John Wiley & Sons, Ltd.

关键词： concurrent objects concurrent programming

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Distributed reachability testing of concurrent programs

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CONCURRENCY AND COMPUTATION-PRACTICE & EXPERIENCE 2010年第18期22卷 2445-2466页

作者： Carver, Richard H. Lei, Yu George Mason Univ Dept Comp Sci Fairfax VA 22030 USA Univ Texas Arlington Dept Comp Sci & Engn Arlington TX 76019 USA

Reachability testing is an approach to verifying concurrent programs. During reachability testing, every partially ordered synchronization sequence of a program with a given input is exercised exactly once. In this paper, we present the design and implementation of a distributed reachability testing algorithm for a cluster of workstations. This algorithm allows different test sequences to be exercised concurrently by different workstations without any synchronization, and without any duplication of sequences among workstations. Dynamic load balancing is performed using a work-stealing scheme. A novel aspect of this scheme is that work-stealing requests progress in rounds. This round-based structure identifies overloaded workstations to target for work stealing. Empirical studies show good speedup for four benchmark Java programs and one Lotos specification. Copyright (C) 2010 John Wiley & Sons, Ltd.

关键词： software testing reachability testing concurrent programming

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On-Chip Active Messages for Speed, Scalability, and Efficiency

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IEEE TRANSACTIONS ON PARALLEL AND DISTRIBUTED SYSTEMS 2015年第2期26卷 507-515页

作者： Harting, R. Curtis Dally, William J. Stanford Univ Dept Elect Engn Stanford CA 94305 USA Nvidia Santa Clara CA USA Stanford Univ Dept Comp Sci Stanford CA 94305 USA

This paper describes and quantifies the benefits of adding low-overhead active messages to many-core, cache-coherent chip-multiprocessors. The active messages we analyze are user defined and trigger the atomic execution of a custom software handler at the destination. Programmers can use these active messages to both move data with less overhead than cache coherency and, more importantly, explicitly send computation to data. Doing so greatly improves (11 x speed, 4.8 x energy) communication idioms such as shared object modification, reductions, data walks, point-to-point communication, and all-to-all communication. Active messages enhance program scalability: applications using them run 63 percent faster with 11 percent less energy on 256 cores. The relative benefits of active messages grow with larger numbers of cores.

关键词： Parallel architecture parallel processors MIMD processors shared memory concurrent programming

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DEVELOPMENT OF A DEBUGGER FOR A concurrent LANGUAGE

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IEEE TRANSACTIONS ON SOFTWARE ENGINEERING 1986年第4期12卷 547-553页

作者： BAIARDI, F DEFRANCESCO, N VAGLINI, G Dipartimento di Informatica Università di Pisa Corso Italia 40 56100 Pisa Italy

The widespread adoption of concurrent languages in software development has called attention to the need for an integrated set of tools to support such an activity. The present analysis focuses attention on some of the issues concerned in debugging concurrent programs. A set of desirable characteristics for a debugger of concurrent languages is deduced from a review of the differences between the debugging of concurrent programs and the debugging of sequential programs. A debugger for the concurrent language ECSP is described. The debugger makes it possible to compare a description of the expected program behavior to the actual program behavior. The description of the program behavior is given in terms of expressions composed by events or assertions on the process state. The developed formalism can describe behaviors at various levels of abstraction. Guidelines for implementation of the debugger are given. A detailed example of program debugging is also provided.

关键词： Debugging Radiation Detectors Delay Process Control Runtime Semantics Parallel Processing Tool Transparency concurrent programming Debugging programming Environment Program Specifications

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