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1

Elimination of task starvation in conflictless scheduling concept

Smoliński M.

Information Systems in Management

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2016

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Vol. 5, No. 2

237--247

EN

New concept of conflictless task scheduling is an alternative approach to existing solutions in concurrency. Conflictless task scheduling includes data structures and algorithm that prevents occurrence of resource conflict between tasks executed in parallel. The range of applications the conflictless task scheduling includes different environments like transactions processing in database management systems, scheduling of processes or threads in operating systems or business processes management. Task scheduling without any resource conflicts is dedicated to high contention of limited resources environments and its algorithm can be implemented in modern GPU. This paper presents concept of local task scheduling without resources conflicts occurrence, discusses features of new approach and focuses on problem of task starvation. Elimination of task starvation is included in conflictless task scheduling concept, detailed explanation are contained in this paper.

2

Transaction mechanisms in complex business processes

Jankiewicz K., Kujawiński K., Mor M., Morzy T.

Control and Cybernetics

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2011

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Vol. 40, no 3

605-625

EN

The importance of systems based on the SOA architecture continues to grow. At the same time, in spite of the existence of many specifications which allow for the coordination of business processes functioning in the SOA environment, there is still lack of solutions that allow the use of system mechanisms of transaction processing. Such solutions should entail the simplification of construction of business processes without affecting their capabilities. This article presents a Transaction Coordinator environment, designed and implemented as a response to these needs.

3

SXCCP+: Simple XML Concurrency Control Protocol for XML Database Systems

Jankiewicz K.

Control and Cybernetics

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2009

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Vol. 38, no 1

215-237

EN

Increasing significance and popularity of XML is the main reason why many commercial object-relational database management systems (ORDBMSs) developed XML storage and processing functionality. Additionally, there are new types of specialized database systems known as 'native' XML database systems. As we know, concurrency control is one of the most important mechanisms in DBMSs. Unfortunately, concurrency control mechanisms, which have been used so far in commercially available native XML DBMSs, offer very low degree of concurrency. The development of universal and effective concurrency control protocol for accessing XML data, with high degree of concurrency, is a necessary condition of the native XML database growth. The aim of this paper is to propose a new concurrency control protocol in XML document access. This protocol is based on primitive operations, which can be treated as a unification platform for any of the XML access methods.

4

Zastosowanie blokad, poziomów izolacji oraz protokołów zarządzania konkurencyjnością do zwiększania wydajności i skalowalności systemów baz danych

Kasper M.

Automatyka / Akademia Górniczo-Hutnicza im. Stanisława Staszica w Krakowie

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2008

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T. 12, z. 1

55-65

PL

Wzrost ilości danych gromadzonych, przechowywanych i przetwarzanych we współczesnych systemach informatycznych wymusił konieczność stosowania coraz bardziej rozbudowanych i złożonych systemów, czego oczywistą konsekwencją jest trudniejsza budowa i zarządzanie takimi systemami. W niniejszym artykule przedstawione zostały trudności występujące podczas realizacji złożonych systemów przetwarzania danych współpracujących ze zcentralizowanymi lub rozproszonymi bazami danych. Znajomość zagadnień opisywanych w artykule pozwala uniknąć niepotrzebnych problemów podczas tworzenia i użytkowania systemów informatycznych współpracujących z bazami danych, gdyż duża część tych utrudnień jest wynikiem fizycznych ograniczeń zrealizowanych systemów baz danych.

EN

Nowadays, increase in number of data gathered, stored and processed in database systems forced us to use complex, complicated systems, which of course causes implementation and maintenance of such systems more difficult. This article presents difficulties that can appear during realization of any complex data processing system which cooperates with centralized or distributed database system. Familiarity with presented issues allow one to avoid unnecessary troubles in creating and maintaining systems working with databases, since many of this inconveniences are caused by database's physical limitations.

5

Przegląd i analiza metod zarządzania współbieżnym dostępem do baz danych dokumentów XML

Jankiewicz K.

Studia Informatica

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2006

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Vol. 27, nr 3

49-105

PL

Dotychczasowe prace w zakresie przetwarzania dokumentów XML koncentrowały się na zagadnieniach: optymalizacja zapytań, transformacja dokumentów, sposoby przechowywania, kompresja dokumentów, normalizacja. Niewiele natomiast zrobiono w zakresie zapewnienia poprawności współbieżnego dostępu i aktualizacji dokumentów XML. Celem tego artykułu jest przegląd i analiza metod zarządzania współbieżnym dostępem do baz danych dokumentów XML.

EN

Existing work on processing of XML documents has been concentrated on: query optimization, storage problems, documents transformation, compressing methods, normalization. There are only few papers concurrency control in accessing and modifying XML documents, which are stored in XML database systems. The aim of this paper is to present survey and analysis of concurrency control methods for XML database systems.

6

Using place invariants to isolate faults in concurrent systems

Tabakow I.

Systems Science

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2003

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Vol. 29, nr 4

99-112

EN

A method of fault isolation in a given concurrent system is presented. First, the system considered is modelled by a live and bounded place-transition Petri net. Then the corresponding net place invariants are computed. The system k-distinguishability measure is obtained in an unique way from the place-invariant matrix. For a large value of k, the system model is extended by using some set of additional places called test points. This is in accordance with the practical requirements introduced. To obtain an 1-distinguishable net the notion of a marked graph component is used. Next, two different diagnosis test strategies are discussed, i.e., combinational and sequential fault diagnosis (assuming MTBF -> infinity and MTTR -> 0, respectively). The approach proposed can be extended for higher level Petri nets, e.g., such as coloured nets or also to design self-diagnosable circuit realisations of Boolean interpreted Petri nets. Several examples are given.

7

Multidatabase global concurrency control algorithms : a performance analysis

Quaglia F., Baldoni R., Ciciani B.

Foundations of Computing and Decision Sciences

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1998

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Vol. 23, No. 1

15-33

EN

The ticket-based concurrency control allows the management of indirect conflicts between multidatabase transactions without violating site autonomy and ensuring global serializability. In this paper, by using discrete event simulation models, we compare two global concurrency control algorithms: the Optimistic Ticket Method (OTM) and the Multidatabase Timestamp Mechanism (MTSM). Performance of those algorithms strongly depend on the local concurrency control scheme at each site. Hence, we propose two optimizations of MTSM: one for the case of timestamp-based local concurrency control, the other for the case of optimistic local concurrency control. The proposed solutions reduce the ticket contention improving performance.