Concurrency (computer science)

In computer science, concurrency is the ability of different parts or units of a program, algorithm, or problem to be executed out-of-order or in partial order, without affecting the outcome. This allows for parallel execution of the concurrent units, which can significantly improve overall speed of the execution in multi-processor and multi-core systems. In more technical terms, concurrency refers to the decomposability of a program, algorithm, or problem into order-independent or partially-ordered components or units of computation. According to Rob Pike, concurrency is the composition of independently executing computations, and concurrency is not parallelism: concurrency is about dealing with lots of things at once but parallelism is about doing lots of things at once. Concurrency is about structure, parallelism is about execution, concurrency provides a way to structure a solution to solve a problem that may (but not necessarily) be parallelizable. A number of mathematical mo

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Formal Treatment of Data Structures in Concurrency Models

The problem of real size system modelling with basic concurrency models like transition systems, Petri nets or process algebra is that there is no possibility to model easily the system data structures. Algebraic specification is a method well adapted to this last aspect and has been chosen to be mixed with the two major concurrency models which are process algebra and Petri nets. We present in this paper how the 'mixing' is done and what are the consequences concerning concurrency through the case of Lotos and Algebraic nets. Our approach is built on a simple case study which is given in several versions with both formalisms. The first one uses the basic models without algebraic specifications to highlight the data structures modelling problem. The second one is used to present how algebraic specifications are integrated in each concurrency model and the last one focuses on the concurrency aspects. Several propositions are then given in order to enhance the mixing of algebraic specifications and Petri nets or process algebra. Keywords : Petri net, process algebra, data types, algebraic specification, algebraic net, Lotos.

1996

Modelling a Secure, Mobile and Transactional System with CO-OPN

Stanislav Chachkov

Modelling complex concurrent systems is often difficult and error-prone, in particular when new concepts coming from advanced practical applications are considered. These new application domains include dynamicity, mobility, security, and localization dependent computing. In order to fully model and prototype such systems we propose to use several concepts introduced in our specification language CO-OPN, like context, dynamicity, mobility, subtyping and inheritance. CO-OPN (Concurrent Object Oriented Petri Net) is a formal specification language for modelling distributed systems; it is based on coordinated algebraic Petri nets. This paper focuses on the use of several basic mechanisms of CO-OPN for modelling mobile systems and the generation of corresponding Java code. A significant example of distributors accessible through mobile devices (for example, PDA with Bluetooth) is fully modelled and implemented with our technique.

IEEE CS Press2003

From Formal Specifications to Ready-to-Use Software Components: The Concurrent Object-Oriented Petri Net Approach

Stanislav Chachkov

CO-OPN (Concurrent Object Oriented Petri Net) is a formal specification language for modelling distributed systems; it is based on coordinated algebraic Petri nets. In this paper we describe a method for generating an executable prototype from a CO-OPN specification. We focus our discussion on the generation of executable code for CO-OPN classes. CO-OPN classes are defined using Petri Nets. The main problems arise when implementing synchronization and non-determinism of CO-OPN classes in procedural languages. Our method proposes a solution to these problems. Another interesting aspect of our method is the easy integration of a generated prototype into any existing system. This paper focuses on the generation of Java code that fulfils the Java Beans component architecture, however our approach is also applicable to other object-oriented implementation languages with a component architecture.

IEEE Computer Society Press2001

Concurrent computing

Concurrent computing is a form of computing in which several computations are executed concurrently—during overlapping time periods—instead of sequentially—with one completing before the next starts.

Parallel computing

Parallel computing is a type of computation in which many calculations or processes are carried out simultaneously. Large problems can often be divided into smaller ones, which can then be solved a

Actor model

The actor model in computer science is a mathematical model of concurrent computation that treats an actor as the basic building block of concurrent computation. In response to a message it receives

CS-322: Introduction to database systems

This course provides a deep understanding of the concepts behind data management systems. It covers fundamental data management topics such as system architecture, data models, query processing and optimization, database design, storage organization, and transaction management.

CS-307: Introduction to multiprocessor architecture

Multiprocessors are a core component in all types of computing infrastructure, from phones to datacenters. This course will build on the prerequisites of processor design and concurrency to introduce the essential technologies required to combine multiple processing elements into a single computer.

CS-453: Concurrent algorithms

With the advent of multiprocessors, it becomes crucial to master the underlying algorithmics of concurrency. The objective of this course is to study the foundations of concurrent algorithms and in particular the techniques that enable the construction of robust such algorithms.