Model-Based Proactive Read-Validation in Transaction Processing Systems

Concurrency control protocols based on read-validation schemes allow transactions which are doomed to abort to still run until a subsequent validation check reveals them as invalid. These late aborts do not favor the reduction of wasted computation and can penalize performance. To counteract this problem, we present an analytical model that predicts the abort probability of transactions handled via read-validation schemes. Our goal is to determine what are the suited points-along a transaction lifetime-to carry out a validation check. This may lead to early aborting doomed transactions, thus saving CPU time. We show how to exploit the abort probability predictions returned by the model in combination with a threshold-based scheme to trigger read-validations. We also show how this approach can definitely improve performance-leading up to 14 % better turnaround-as demonstrated by some experiments carried out with a port of the TPC-C benchmark to Software Transactional Memory

Reversible Computation: Extending Horizons of Computing

This open access State-of-the-Art Survey presents the main recent scientific outcomes in the area of reversible computation, focusing on those that have emerged during COST Action IC1405 "Reversible Computation - Extending Horizons of Computing", a European research network that operated from May 2015 to April 2019. Reversible computation is a new paradigm that extends the traditional forwards-only mode of computation with the ability to execute in reverse, so that computation can run backwards as easily and naturally as forwards. It aims to deliver novel computing devices and software, and to enhance existing systems by equipping them with reversibility. There are many potential applications of reversible computation, including languages and software tools for reliable and recovery-oriented distributed systems and revolutionary reversible logic gates and circuits, but they can only be realized and have lasting effect if conceptual and firm theoretical foundations are established first

The European Regional Policy in Hungary. An Evaluation of the Objectives and Instruments for the Cohesion

The paper underlines the progresses Hungary undertook during the pre-accession process and after the European Union membership in regional economic development. Using official documents of the European Institutions, statistical data provided by Inforegio, Eurostat, the Hungarian National Institute of Statistics, FADN-DG Agriculture and AKI Ive evaluated the impact of the European objectives and instruments for the cohesion (Structural funds and the Cohesion fund) on the convergence of the Country with the European parameters. The results obtained show a slow evidence of economic convergence but also the emergence and increase of internal divergence between winning and loosing counties, these last being prevalently agricultural, with problems of re-conversion increased by the effects of the post- 1989 legislative provisions. This outcome derives party from the lack of projecting abilities (and opportunism) of the Hungarian governments but its also linked to the often unsuitable guidelines and weak monitoring of the European Institutions.European regional policy, convergence, cohesion, agricultural reforms., Community/Rural/Urban Development,