On the Design of a Language for Programming Real-Time Concurrent Processes

ILIAD is a high-evel language for programming real-time applications which involve concurrent processing. It was designed to help scientists and engineers write reliable programs that can be read and maintained. An ILIAD program consists of a group of concurrent tasks. The tasks are autonomous and must cooperate in using the shared memory and devices in the execution environment. The language has facilities for providing secure access to these resources and for creating and synchronizing parallel instruction streams. In providing an overview of the language, the factors motivating the major design choices are discussed. A programming example illustrates how ILIAD might be applied. An assessment of the language includes a discussion of potential problem areas, both technical and nontechnical.     

关于网络程序设计中的并发复杂性研究

随着科学技术的飞速发展,互联网成为现今社会不可或缺的重要信息基础设施,但网络环境下的并发性问题,也成为传统网络程序在设计开发过程中的严重阻碍,降低了网络程序的开发效率。并发性问题对网络程序设计造成的重大影响,与多核处理器引起的＂软件并发危机＂影响是一致的,而并发问题也一直没有得到彻底解决。本文主要研究网络程序设计中的并发复杂性,为类似研究提供一些参考。     

A Note on Concurrent Programming Control

An extension to Dijkstra's solution [1], of the problem of limiting access by multiple processors to a single resource, is described. The solution has similar delay characteristics to Ferguson's solution [3] while using less complex data structures. Some claims in [3] are examined.     

Communication Port: A Language Concept for Concurrent Programming

A new language concept–communication port (CP), is introduced for programming on distributed processor networks. Such a network can contain an arbitrary number of processors each with its own private storage but with no memory sharing. The processors must communicate via explicit message passing. Communication port is an encapsulation of two language properties: "communication non-determinism" and "communication disconnect time." It provides a tool for progranmers to write well-structured, modular, and efficient concurrent programs. A number of examples are given in the paper to demonstrate the power of the new concepts.     

并行工程系统集成方法的比较与应用研究

以并行工程的实践经验为基础,总结了并行工程系统集成4个方面的需求。比较了基于数据库、中间件、STE以及Agent等4种相关的系统集成技术,指出了它们的优缺点及适用范围,从而为并行工程系统集成技术的选择提供了重要的参考。目前,这些方法在航天并行工程和齐齐哈尔并行工程中都得到不同程度的应用,该文分析了它们在应用中存在的问题,并结合国外的有关研究,指出了解决这些问题的方法和进一步的研究方向。     

Concurrent Programming Technologies and Techniques

Intensive use of computer experiments in modern science introduces qualitative changes into experimental resources. This implies the change in techniques used to solve relevant problems. An analysis of technological chains (from the problem statement to its solution) shows that often a particular problem can be solved in a variety of ways with the use of modern multiprocessor computers, which are also called supercomputers. The multiplicity of approaches to solving a problem requires that researches possess certain skills in using supercomputers. It is difficult for novice users of multiprocessor computers to find bearings when developing software for solving applied problems. The practice shows that main difficulties reveal themselves when it is required to develop portable and efficient parallel software. This is because tools that facilitate the development and provide full access to debugging information have yet to be elaborated. Actually, the problem is in the absence of standards for development and debugging tools for supercomputers, which is explained by the fact that computer science is yet young. For the same reason, no logically complete basic texts for concurrent programming courses for novices are available. On the basis of Russian-language literature, an attempt is made at setting up beacons that mark certain common and promising technologies in using supercomputers. The emphasis is made on problems encountered by programmers when solving applied problems with the use of supercomputers. The development of multiprocessor computers is closely related to concurrent programming technologies, both universal and oriented to specific supercomputer architectures. By programming technology, i.e., by memory management, we mean the use of tools designed for managing a particular computer system. It should be noted that when developing software for supercomputers (both management software and programs for solving applied problems), one must pay special attention to programming technique, i.e., to designing the logical architecture of a program. This implies the development and extending parallelizing algorithms, which enhances the efficiency of execution on multiprocessor computers. This review was compiled on the basis of publications in Russian journals and in the Russian Internet zone.     

Trellis Processes : A Compact Representation for Runs of Concurrent Systems

The unfolding of a concurrent system represents in a compact manner all possible runs of this system. Unfoldings are used in many applications, ranging from model-checking (offline) to failure diagnosis (on-line). Their factorization properties form the basis of modular/distributed algorithms to achieve these tasks. The trellis structure proposed here is an alternate and more compact representation for the trajectory set of a concurrent system. In this structure, time is unfolded, but not the conflict relations. Trellis nets are the generalization to concurrent systems of the usual notion of trellis for an automaton. As for unfoldings, factorization properties are evidenced on trellises, which makes these more compact structures a possible candidate for distributed model checking or diagnosis algorithms. As an example, we show how trellises can be used for diagnosis purposes in a distributed observation setting.

基于Petri网和并发调度标识图的并发任务调度的建模与分析

在云计算及网格计算环境下,由于资源具有分布、异构、动态、自治等特点,其并发任务的调度更加复杂,迫切需要强有力的图形与数学工具对其进行建模与分析。Petri网是描述与分析并发、异步、动态等事件的理想的图形与数学工具。给出了并发任务调度的加权时延Petri网模型。可达标识图是分析Petri网动态特性的一个重要工具,但它不能表达Petri网中变迁的并发关系,尤其是不便于分析被描述系统的时间特性。提出了并发调度标识图的概念,给出了构造时延Petri网的并发调度标识图的算法。最后,利用并发调度标识图分析了并行下载的时间特性。     

Nautilus, a Concurrent Diagrammatic Specification and Programming Language

Nautilus is a high-level specification and programming language having abstraction mechanisms not commonly found in other programming languages inspired by its semantic domain (a categorial model named Nonsequential Automata). It constitutes an elegant solution for concurrency and non-determinism as well as for synchronization of concurrent systems. The role as specification language highlights the diagrammatic syntax (it was originally text based).The diagrammatic syntax for Nautilus allows complete programs to be written using symbols and graphical diagrams. The graphical notation was elaborated in order to be able to express all the structures in the language, yet trying to improve the visualization of written programs. A brief comparison with UML is included. To support Nautilus as a programming language, a mapping to Java is constructed, setting the basis for an execution environment of Nautilus specifications.     

A Fully Abstract Semantics for Concurrent Constraint Programming

A compositional and fully abstract semantics for concurrent constraint programming is developed. It is the first fully abstract semantics which takes into account both non-determinism, infinite computations, and fairness. We present a simple concurrent constraint programming language, whose semantics is given by a set of reduction rules augmented with fairness requirements. In the fully abstract semantics we consider two aspects of a trace, viz. the function computed by the trace (the functionality) and the set of input and output data (the limit of the trace). We then derive the fully abstract semantics from the set of traces using a closure operation. We give two proofs of full abstraction; the first relies on the use of a syntactically infinite context. The second proof requires only a finite context, but assumes as input a representation of the function to be computed by the context. Finally, we examine the algebraic properties of the programming language with respect to the fully abstract semantics. It turns out that the non-deterministic selection operation can be defined using operations derived from parallel composition and the usual set-theoretic operations on sets of traces.     

Special Feature A Keynote Address on Concurrent Programming

Delivered at COMPSAC 78, this address draws a parallel between the major development phases of the first 20 years of concurrent programming and the present challenge of distributed computing.     

DSML4CP: A Domain-specific Modeling Language for Concurrent Programming

Nowadays, concurrent programs are an inevitable part of many software applications. They can increase the computation performance of the applications by parallelizing their computations. One of the approaches to realize the concurrency is using multi thread programming. However, these systems are structurally complex considering the control of the parallelism (such as thread synchronization and resource control) and also considering the interaction between their components. So, the design of these systems can be difficult and their implementation can be error-prone especially when the addressed system is big and complex. On the other hand, a Domain-specific Modeling Language (DSML) is one of the Model Driven Development (MDD) approaches which tackles this problem. Since DSMLs provide a higher abstraction level, they can lead to reduce the complexities of the concurrent programs. With increasing the abstraction level and generating the artifacts automatically, the performance of developing the software (both in design and implementation phases) is increased, and the efficiency is raised by reducing the probability of occurring errors. Thus, in this paper, a DSML is proposed for concurrent programs, called DSML4CP, to work in a higher level of abstraction than code level. To this end, the concepts of concurrent programs and their relationships are presented in a metamodel. The proposed metamodel provides a context for defining abstract syntax, and concrete syntax of the DSML4CP. This new language is supported by a graphical modeling tool which can visualize different instance models for domain problems. In order to clarify the expressions of the language; the static semantic controls are realized in the form of constraints. Finally, the architectural code generation is fulfilled via model transformation rules using the templates of the concurrent programs. To increase level of the DSML׳s leverage and to demonstrate the general support of concurrent programming by the DSML, the transformation mechanism of the tool supports two well-known and highly used programming languages for code generation; Java and C#. The performed experiments on two case studies indicate a high performance for proposed language. In this regard, the results show automatic generation of 79% of the final code and 86% of the functions/modules on average.     

Aligning Strategies, Processes, and it: A Case Study

Hewlett-Packard Co. developed a framework for aligning business and IT strategy. It has allowed the company to make process changes regardless of the limitations of existing technology and it makes visible the changes new technologies and processes have on each other. Most important, the framework enjoys a high level of commitment from people throughout the organization.     

Stochastic Concurrent Constraint Programming and Differential Equations

We tackle the problem of relating models of systems (mainly biological systems) based on stochastic process algebras (SPA) with models based on differential equations. We define a syntactic procedure that translates programs written in stochastic Concurrent Constraint Programming (sCCP) into a set of Ordinary Differential Equations (ODE), and also the inverse procedure translating ODE's into sCCP programs. For the class of biochemical reactions, we show that the translation is correct w.r.t. the intended rate semantics of the models. Finally, we show that the translation does not generally preserve the dynamical behavior, giving a list of open research problems in this direction.     

基于深度学习的跨自然语言与程序语言生成任务综述

近年来,随着人工智能技术的发展,许多编程人员期望计算机代替他们自动完成程序代码或者代码注释的编写等任务。跨自然语言与程序语言(Natural languages and programming languages, NL-PL)生成即为此类任务,指自然语言和程序语言之间的相互转换任务,包括自然语言到程序语言的生成和程序语言到自然语言的生成两类任务。最近几年,跨NL-PL生成在研究与应用方面呈现出爆发式的增长,尤其是随着深度学习(Deep learning,DL)技术的发展,越来越多研究人员开始利用DL技术来提升跨NL-PL生成任务效果。他们通过优化程序表示方式、改进神经网络模型以及设计大型预训练模型等方法,在该领域取得了众多突破性的进展。在基于DL的跨NL-PL生成技术获得迅猛发展的同时,大型互联网公司逐渐将该领域的研究成果付诸商用,因此,模型应用安全性也受到了学术界和业界的紧密关注。为了进一步系统地研究跨NL-PL生成技术,对这些已有的成果进行梳理非常必要。本文以程序生成和注释生成这两类典型跨NL-PL生成任务为切入点,对该领域具有代表性的最新文献进行归纳总结。我们从众多已有参考文献...     

一种在MPI程序中实现点对点通信原语到集合通信原语转换的方法

针对当前存在的大量非结构化MPI程序,该文提出一种在MPI程序中实现点对点通信原语到集合通信原语转换的方法,其基本思路是:分析非结构化消息传递并行代码的内部结构,建立Diophantine不等式系统,然后用Omega库运算得到点对点通信代码段的通信模式集,再辅以数据交换分析确定对应的集合通信原语并替换。     

A Comparative Study and Evaluation of Parallel Programming Models for Shared-Memory Parallel Architectures

Nowadays, shared-memory parallel architectures have evolved and new programming frameworks have appeared that exploit these architectures: OpenMP, TBB, Cilk Plus, ArBB and OpenCL. This article focuses on the most extended of these frameworks in commercial and scientific areas. This paper shows a comparative study of these frameworks and an evaluation. The study covers several capacities, such as task deployment, scheduling techniques, or programming language abstractions. The evaluation measures three dimensions: code development complexity, performance and efficiency, measure as speedup per watt. For this evaluation, several parallel benchmarks have been implemented with each framework. These benchmarks are created to cover certain scenarios, like regular memory access or irregular computation. The conclusions show some highlights, like the fact that some frameworks (OpenMP, Cilk Plus) are better for transforming quickly a sequential code, others (TBB) have a small footprint which is ideal for small problems, and others (OpenCL) are suited for heterogeneous architectures but they require a very complex development process. The conclusions also show that the vectorization support is more critical than multitasking to achieve efficiency for those problems where this approach fits.