• Title, Summary, Keyword: Concurrency

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A Hybrid Concurrency Control without Deadlock based on Reordering (재배열 기반의 교착상태 없는 혼성 병행실행제어)

  • Cho, Sung-Ho
    • Journal of Internet Computing and Services
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    • v.7 no.6
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    • pp.79-86
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    • 2006
  • Many of concurrency control for client-sewer database systems have been proposed and studied in the literature. However, commonly known schemes do not manage to the case of dramatic changes in data contention because the data contention of database systems is changed for each cases. In this paper, we propose o hybrid concurrency control. The proposed scheme uses a optimistic scheme for the first-run transactions and a pessimistic scheme for the second-run transactions. By pre-claiming locks in the second phase, deadlocks which ore possible in pessimistic based concurrency control are prevented in our approach. In addition, the scheme ensures at most one re-execution even if the validation in the optimistic phase fails. By a detailed simulation, this paper examines the behaviors of the Distributed Optimistic Concurrency Control and the proposed scheme. The simulation study shows our scheme outperforms Distributed Optimistic Concurrency Control in our experimental result.

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Evaluation Metrics for Class Hierarchy in Object-Oriented Databases: Concurrency Control Perspectives

  • Jun Woo-Chun
    • Journal of Korea Multimedia Society
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    • v.9 no.6
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    • pp.693-699
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    • 2006
  • Object-oriented databases (OODBs) have been adopted for managing non-standard applications such as computer-aided design (CAD), office document management and many multimedia applications. One of the major characteristics of OODBs is class hierarchy where a subclass is allowed to inherit the definitions defined on its superclasses. In this paper, I present the evaluation metrics for class hierarchy quality in OODBs. These metrics are developed to determine if a concurrency control scheme can achieve good performance or not on a given class hierarchy. I first discuss the existing concurrency control schemes for OODBs. Then I provide evaluation metrics based on structural information and access frequency information in class hierarchies. In order to discuss significance of the proposed performance metrics, an analytical model is developed. Analysis results show that the performance metrics are important factor in concurrency control performance. I consider both single inheritance and multiple inheritance. The proposed metrics can be used to provide guidelines on how to design class hierarchy of an OODB for maximizing the performance of concurrency control technique.

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Concurrency Control and Recovery Methods for Multi-Dimensional Index Structures (다차원 색인구조를 위한 동시성제어 기법 및 회복기법)

  • Song, Seok-Il;Yoo, Jae-Soo
    • The KIPS Transactions:PartD
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    • v.10D no.2
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    • pp.195-210
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    • 2003
  • In this paper, we propose an enhanced concurrency control algorithm that maximizes the concurrency of multi-dimensional index structures. The factors that deteriorate the concurrency of index structures are node splits and minimum bounding region (MBR) updates in multi-dimensional index structures. The proposed concurrency control algorithm introduces PLC(Partial Lock Coupling) technique to avoid lock coupling during MBR updates. Also, a new MBR update method that allows searchers to access nodes where MBR updates are being performed is proposed. To reduce the performance degradation by node splits the proposed algorithm holds exclusive latches not during whole split time but only during physical node split time that occupies the small part of a whole split process. For performance evaluation, we implement the proposed concurrency control algorithm and one of the existing link technique-based algorithms on MIDAS-3 that is a storage system of a BADA-4 DBMS. We show through various experiments that our proposed algorithm outperforms the existing algorithm in terms of throughput and response time. Also, we propose a recovery protocol for our proposed concurrency control algorithm. The recovery protocol is designed to assure high concurrency and fast recovery.

A Study on Solution of Anomaly due to Integrated of Inheritance and Concurrency (상속성과 병행성에서 오는 상속변칙 문제 해결에 관한 연구)

  • Park, Young-Ok;Moon, Jeong-Hwan;Lee, Chiol-Seong;Hong, Seong-Pyo;Lee, Ho-Young;Lee, Joon
    • Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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    • pp.485-489
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    • 2002
  • The concepts from OOP have been integrated in a concurrency, leading to the emergence of concurrent OOP. Concurrency of concurrent OOP and various model technique of OOP language are integrated had been proposed. Concurrent programming and OOP technique unite that can gain various kinds advantage to develop concurrency application program. There have been a number of models proposed for integrating concurrency and OOP However, concurrency and inheritance are two paradigms which are difficult to combine in a suitable manner. The inheritance anomaly is the conclicted phenomena, which occurs only when concurrency is integrated with inheritance. The inheritance anoay is referred to as the serious difficulty in integrating inheritance and concurrency in a simple and efficient manner within a concurrent OOP. Concurrency and inheritance with integrated that Drop reusability of object remarkably and require re-justice of code that is inherited in subclass. So concurrency and inheritance with integrated Collision that happen between two special qualitys or Interference phenomenon is inheritance anomaly. Effect of inheritance anomaly minimum Much study findings announced about access method to improve code reusability. Wish to approach in paper that is division by synchronization code and method code to solve interference problem between and concurrency.

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Development and Performance Evaluation of a Concurrency Control Technique in Object-Oriented Database Systems

  • Jun, Woochun;Hong, Suk-Ki
    • KSII Transactions on Internet and Information Systems (TIIS)
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    • v.12 no.4
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    • pp.1899-1911
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    • 2018
  • In this work, we propose a concurrency control scheme in object-oriented database (OODB). Since an OODB provides complex modeling power than the conventional relational databases, a concurrency control technique in OODB is also rather complicated and has influence on the overall performance. Thus, it is very important to develop a concurrency control technique with less overhead. The proposed scheme deals with class hierarchy that is a key concept in OODBs. The proposed scheme is developed on implicit locking scheme. Also, the proposed scheme is designed using data access frequency in order to reduce locking overhead than implicit locking. It means that, if access frequency information is not available, the proposed scheme works just like the existing implicit locking, In our work, the correctness of the proposed scheme is proved. The performance is analyzed depending on access types. Also, it is proved that our scheme performs works much better than the implicit locking does.

Analysis of Inheritance Anomaly due to Integrated of Inheritance and Concurrency (상속성과 병행성 통합에서 오는 상속 변칙 분석)

  • 오승재
    • Journal of the Korea Society of Computer and Information
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    • v.6 no.4
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    • pp.38-44
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    • 2001
  • The integration of concurrency and object-oriented programming paradigm has been a goal of researchers for over a decade. The concurrent object-oriented programming languages used for various concurrent applications development. However, concurrency and inheritance have conflicting characteristics, thereby inhibiting their simultaneous use without heavy breakage of encapsulation. This conflicting phenomenon is known as inheritance anomalies, have been limited in applicability and have not addressed all the issues that synchronization raises. In this paper, the behavior description equation is introduced for the solution for the conflicting phenomenon, between inheritance and object-based concurrency. As a result, it can solve the several inheritance anomalies and is not necessary to redefine method. Therefor, it offers flexible concurrency model with an emphasis on the reuse of both synchronization and function code.

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Development of Performance Evaluation Metrics of Concurrency Control in Object-Oriented Database Systems

  • Jun, Woochun;Hong, Suk-Ki
    • Journal of Internet Computing and Services
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    • v.19 no.5
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    • pp.107-113
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    • 2018
  • Object-oriented databases (OODBs) canbe used for many non-traditional database application areas such as computer-aided design, etc. Usually those application areas require advanced modeling power for expressing complicated relationships among data sets. OODBs have more distinguished features than the traditional relational database systems. One of the distinguished characteristics of OODBs is class hierarchy (also called inheritance hierarchy). A class hierarchy in an OODB means that a class can hand down the definitions of the class to the subclass of the class. In other words, a class is allowed to inherit the definitions of the class from the superclass. In this paper, we present performance evaluation metrics for class hierarchy in OODBs from a concurrency control perspective. The proposed performance metrics are developed to determine which concurrency control scheme in OODBs can be used for a given class hierarchy. In this study, in order to develop performance metrics, we use class hierarchy structure (both of single inheritance and multiple inheritance), and data access frequency for each class. The proposed performance metrics will be also used to compare performance evaluation for various concurrency control techniques.

Concurrency Control Protocol for Main Memory Database Systems (주기억 데이터베이스 시스템을 위한 병행수행 제어 프로토콜)

  • Sim, Jong-Ik;Bae, Hae-Yeong
    • The Transactions of the Korea Information Processing Society
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    • v.3 no.7
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    • pp.1687-1696
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    • 1996
  • Most of the main memory database systems use two-phase locking(2PL)for concurrency control. The 2PL method is preferred over other methods for concurrency control because of its simplicity and common usage. However, conventional concurrency control solution will function poorly when the data are memory resident. In this paper, we propose a new optimistic concurrency control protocol for a main memory database system. In our proposed protocol, transaction conflict information is used in validation phase to improve data conflict resolution decisions. Our experiments show that the proposed protocol performs better than 2PL in terms of throughput for main memory database system enshrinements.

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Object Picking and Concurrency for Collaborative Design System (협동설계시스템을 위한 오브젝트 Picking Concurrency)

  • 윤보열;송승헌;김응곤
    • Proceedings of the Korean Information Science Society Conference
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    • pp.631-633
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    • 2001
  • 협동설계시스템에서의 공유 오브젝트는 3D 도형이 되며, 사용자가 임의의 오브젝트를 picking하는 문제와 그 오브젝트에 어떤 조작을 취할 때 동시성제어(concurrency)하는 문제가 생긴다. 본 논문에서는 오브젝트의 picking이 마우스 포인터에서의 ray와 오브젝트간에 intersection을 계산하는 방법 외에 scene graph의 노드에 picking 속성을 주는 방법, bounds를 설정하는 방법, picking test의 범위를 한정하는 방법을 사용하여 computation의 부담을 줄이고 효과적인 동시성제어가 이루어지도록 action에 따라 공유(shared)lock과 전용(exclusive)lock을 사용한다.

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Comparison Analysis of Concurrency Control Algorithms by using Selection Models (선택모델을 이용한 동시성제어 알고리즘 비교 분석)

  • Yang, Gi-Chul
    • The KIPS Transactions:PartA
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    • v.10A no.2
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    • pp.131-136
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    • 2003
  • Comparison criteria and a selection model for concurrency control algorithms has been presented in this article. In addition, a comparison analysis has been performed with the developed comparison model. The result of the analysis can be utilized to select the best fitting concurrency control algorithm to the user's existing system environment.