Using heuristic search for finding deadlocks in concurrent systems

AbstractModel checking is a formal technique for proving the correctness of a system with respect to a desired behavior. This is accomplished by checking whether a structure representing the system (typically a labeled transition system) satisfies a temporal logic formula describing the expected behavior. Model checking has a number of advantages over traditional approaches that are based on simulation and testing: it is completely automatic and when the verification fails it returns a counterexample that can be used to pinpoint the source of the error. Nevertheless, model checking techniques often fail because of the state explosion problem: transition systems grow exponentially with the number of components. The aim of this paper is to attack the state explosion problem that may arise when looking for deadlocks in concurrent systems described through the calculus of communicating systems. We propose to use heuristics-based techniques, namely the A* algorithm, both to guide the search without constructing the complete transition system, and to provide minimal counterexamples. We have realized a prototype tool to evaluate the methodology. Experiments we have conducted on processes of different size show the benefit from using our technique against building the whole state space, or applying some other methods

DELFIN+: An efficient deadlock detection tool for CCS processes

AbstractModel checking is a formal technique for proving the correctness of a system with respect to a desired behavior. However, deadlock detection via model checking is particularly difficult for the following two problems: (i) the state explosion problem, due to the exponential increase in the size of a finite state model as the number of system components grows; and (ii) the output interpretation problem, as often counter-examples are so long that they are hard to understand. The aim of this paper is to solve both problems by using heuristic-based search strategies. We have realized DELFIN+ (DEadLock FINder) a tool supporting efficient deadlock detection in CCS processes. We have used this tool to verify a sample of CCS processes, in order to evaluate the method on them

Model Checking Multithreaded Programs by Means of Reduced Models

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Methodological Issues in a Cmm Level 4 Implementation

The Capability Maturity Model (CMM) developed by the Software Engineering Institute is an improve-ment paradigm. It provides a framework for assessing the maturity of software processes on a five level scale, and guidelines which help to improve software process and artifact quality. Moving towards CMM Level 4 and Level 5, is a very demanding task even for large software companies already accustomed to the CMM and ISO certifications. It requires, for example, quality monitoring, control, feedback, and process optimiza-tion. In fact, going beyond CMM Level 3 requires a radical change in the way projects are carried out and managed. It involves quantitative and statistical techniques to control software processes and quality, and it entails substantial changes in the way the organization approaches software life cycle activities. In this paper we describe the process changes, adaptation, integration and tailoring, and we report lessons learned while preparing an Italian solution centre of EDS for the Level 4 internal assessment. The solution centre has about 350 people and carries out about 40 software development and maintenance projects each year. We describe how Level 4 Key Process Areas have been implemented building a methodological frame-work which leverages both existing available methodologies and practices already in place (e.g., derived form ISO compliance). We discuss how methodologies have been adapted to the company’s internal and external situation and what are the underlining assumptions for the methodology adaptation. Furthermore we discuss cultural and organizational changes required to obtain a CMM Level 4 certification. The steps and the process improvement we have carried out, and the challenges we have faced were most likely those whith the highest risk and cost driving factor common to all organizations aiming at achieving CMM Leve