3,677 research outputs found
Unlocking Blocked Communicating Processes
We study the problem of disentangling locked processes via code refactoring.
We identify and characterise a class of processes that is not lock-free; then
we formalise an algorithm that statically detects potential locks and propose
refactoring procedures that disentangle detected locks. Our development is cast
within a simple setting of a finite linear CCS variant \^a although it suffices
to illustrate the main concepts, we also discuss how our work extends to other
language extensions.Comment: In Proceedings WWV 2015, arXiv:1508.0338
Hidden and Uncontrolled - On the Emergence of Network Steganographic Threats
Network steganography is the art of hiding secret information within innocent
network transmissions. Recent findings indicate that novel malware is
increasingly using network steganography. Similarly, other malicious activities
can profit from network steganography, such as data leakage or the exchange of
pedophile data. This paper provides an introduction to network steganography
and highlights its potential application for harmful purposes. We discuss the
issues related to countering network steganography in practice and provide an
outlook on further research directions and problems.Comment: 11 page
A Compositional Approach for Schedulability Analysis of Distributed Avionics Systems
This work presents a compositional approach for schedulability analysis of
Distributed Integrated Modular Avionics (DIMA) systems that consist of
spatially distributed ARINC-653 modules connected by a unified AFDX network. We
model a DIMA system as a set of stopwatch automata in UPPAAL to verify its
schedulability by model checking. However, direct model checking is infeasible
due to the large state space. Therefore, we introduce the compositional
analysis that checks each partition including its communication environment
individually. Based on a notion of message interfaces, a number of message
sender automata are built to model the environment for a partition. We define a
timed selection simulation relation, which supports the construction of
composite message interfaces. By using assume-guarantee reasoning, we ensure
that each task meets the deadline and that communication constraints are also
fulfilled globally. The approach is applied to the analysis of a concrete DIMA
system.Comment: In Proceedings MeTRiD 2018, arXiv:1806.09330. arXiv admin note: text
overlap with arXiv:1803.1105
The Let Me Learn Process® : a robust theory with practical implications
This paper reviews a learning system that has withstood empirical tests of its theoretical and psychometric robustness. The system includes both an instrument that serves as an important tool to launch the process as well as a system of skills that empower learners to interact effectively with the learning environment and ensure successful learning. This article traces critical reviews of published learning styles models and juxtaposes them with research conducted on the Let Me Learn Process to test the robustness of the theory that supports it. The author contends that the Let Me Learn Process has a strong theoretical and psychometric base thus giving what it claims to give, namely, a robust and inclusive theoretical foundation, a comprehensive lexicon of terms that provide a means of communicating one’s experience of learning, an explanation of learning which fosters a learner’s responsibility, and finally empirical evidence revealing a measurable difference in the behaviour of learners.peer-reviewe
Static Analysis of Run-Time Errors in Embedded Real-Time Parallel C Programs
We present a static analysis by Abstract Interpretation to check for run-time
errors in parallel and multi-threaded C programs. Following our work on
Astr\'ee, we focus on embedded critical programs without recursion nor dynamic
memory allocation, but extend the analysis to a static set of threads
communicating implicitly through a shared memory and explicitly using a finite
set of mutual exclusion locks, and scheduled according to a real-time
scheduling policy and fixed priorities. Our method is thread-modular. It is
based on a slightly modified non-parallel analysis that, when analyzing a
thread, applies and enriches an abstract set of thread interferences. An
iterator then re-analyzes each thread in turn until interferences stabilize. We
prove the soundness of our method with respect to the sequential consistency
semantics, but also with respect to a reasonable weakly consistent memory
semantics. We also show how to take into account mutual exclusion and thread
priorities through a partitioning over an abstraction of the scheduler state.
We present preliminary experimental results analyzing an industrial program
with our prototype, Th\'es\'ee, and demonstrate the scalability of our
approach
Predicting and witnessing data races using CSP
Detecting and debugging data races is a complex task due to the large number of interleavings possible in a parallel program. Most tools can find the data races reliably in an observed execution, but they miss errors in alternative reorderings of events. In this paper we describe an automated approach to generate, from a single program trace, a model in CSP with alternative interleavings. We check for data races patterns and obtain a witness that allows the reproduction of errors. Reproduction reduces the developer effort to correct the error
Recommended from our members
Programming Shared Memory Multiprocessors with Deterministic Message-Passing Concurrency: Compiling SHIM to Pthreads
Multicore shared-memory architectures are becoming prevalent and bring many programming challenges. Among the biggest are data races: accesses to shared resources that make a program's behavior depend on scheduling decisions beyond its control. To eliminate such races, the SHIM concurrent programming language adopts deterministic message passing as it sole communication mechanism. We demonstrate such language restrictions are practical by presenting a SHIM to C-plus-Pthreads compiler that can produce efficient code for shared-memory multiprocessors. We present a parallel JPEG decoder and FFT exhibiting 3.05 and 3.3times speedups on a four-core processor
- …