Deadlock detection in distributed database systems: a new algorithm and a comparative performance analysis

This paper attempts a comprehensive study of deadlock detection in distributed database systems. First, the two predominant deadlock models in these systems and the four different distributed deadlock detection approaches are discussed. Afterwards, a new deadlock detection algorithm is presented. The algorithm is based on dynamically creating deadlock detection agents (DDAs), each being responsible for detecting deadlocks in one connected component of the global wait-for-graph (WFG). The DDA scheme is a “self-tuning” system: after an initial warm-up phase, dedicated DDAs will be formed for “centers of locality”, i.e., parts of the system where many conflicts occur. A dynamic shift in locality of the distributed system will be responded to by automatically creating new DDAs while the obsolete ones terminate. In this paper, we also compare the most competitive representative of each class of algorithms suitable for distributed database systems based on a simulation model, and point out their relative strengths and weaknesses. The extensive experiments we carried out indicate that our newly proposed deadlock detection algorithm outperforms the other algorithms in the vast majority of configurations and workloads and, in contrast to all other algorithms, is very robust with respect to differing load and access profiles. Received December 4, 1997 / Accepted February 2, 1999     

一种基于移动Agent技术的分布式死锁检测算法

死锁的处理长期以来一直是分布式系统的研究重点,已有许多成熟算法.随着网络技术的发展,越来越多的客户和资源可在网络中自由移动,这种可移动性使得传统算法面临了新的挑战.在这种新的应用背景下,本文结合移动Agent技术,提出了一种分布式系统死锁检测和解除算法：Agent Guard.该算法使用一个移动Agent,使其遵循一定的路线算法在各个站点间移动来收集资源请求和分配信息并进行分析,从而发现并解除死锁.模拟实验证明,A-gent Guard算法能取得较短的死锁持续时间,较小的伪死锁率,且网络的通信复杂度也有降低.     

对于避免死锁的安全算法的改进

在每种资源只有一个个体的情况下,本文给出了一种避免死销的安全算法。该算法是对现有的一种安全算法的改进,改进后的算法被命名为触网式安全算法,该算法把以前算法的运算级次从n^2(n表示系统中进程的数目）降低为n,从而大大地节省了检测开锁。     

分布式死锁检测算法中伪死锁率的研究和改进

死锁处理是分布式系统中的关键问题,其中处理死锁最主要的手段为死锁检测。在评价死锁检测算法性能时伪死锁率被视为一项重要指标,故降低伪死锁率对提高算法性能有着促进作用,而目前大多数算法改进对伪死锁率关注较少。本文阐述了伪死锁研究的意义,并对若干种死锁检测算法的伪死锁率进行研究和模拟实验,认为现有的死锁算法可分为两类:环内检测和环无关检测。并分别通过减少冗余消息和本地死锁解决两种改进方法来降低目前算法的伪死锁率,最终实验表明算法性能获得较大提高。     

A partially distributed deadlock detection algorithm

In this paper, a partially distributed deadlock detection algorithm [PDDDA] with multiple outstanding requests is presented for use in distributed database systems. This algorithm allows a process to request many resources simultaneously and uses a central controller for detecting multisite deadlocks. The detection of local deadlocks and the maintenance of local deadlock information are performed at each of the local sites. This partially distributed algorithm alleviates the problem of congestion at the central controller in a centralized algorithm and needs fewer messages and smaller storage space than a fully decentralized algorithm. A set of criteria for comparing deadlock detection algorithms are also given and then used to compare PDDDA with a fully decentralized algorithm proposed by Isloor and Marsland.Research reported herein was supported by US Army CECOM, Ft. Monmouth, New Jersey, under Contract No. DAAB07-83-K-K542. The views, opinions, and/or findings contained in this paper are those of the authors and should not be construed as an official Deportment of the Army position, policy or decision.     

容错的分布式系统通用死锁模型检测解除算法

分布式系统技术为采用低成本购建高性能系统提供了有效的途径,但是由于资源的分配与需求可能产生冲突,造成系统中发生死锁,导致系统运行陷入停滞.在不可靠的分布式系统中,故障会干扰正常的死锁检测,但现有的死锁检测算法不具有容错功能.对失效形式进行了归类,提出一个容错的死锁检测解除算法.算法建立在通用的AND-OR 模型基础上,采用扩散计算和集中规约方式,不仅能够检测到死锁,而且能给出死锁环的全部成员.若死锁拓扑处于静态且为环状,算法的消息复杂度的上限为e+n-1,时间复杂度为d,其中e为死锁等待图中边的个数,n和d为构成死锁环的节点的个数,分析表明算法性能等于或优于同类算法.     

Controller design and performance evaluation for deadlock avoidance in automated flexible manufacturing cells

In this paper, the design of a deadlock avoidance controller is described. The uncontrolled system is modeled using colored Petri nets. The system controller is based on a restrictive (not maximally permissive) deadlock avoidance policy to resolve deadlocks and control the real-time resource allocation decisions in the system. Performance evaluation of systems controlled by not maximally permissive algorithms is essential in determining the applicability and effectiveness of the control algorithms. The performance of the controlled system is compared with performance of optimal control policies to quantify the effects of the restrictiveness of the deadlock avoidance policy on system performance.     

Tool integration for flexible simulation of distributed algorithms

Over the last two decades, considerable research has been done in distributed operating systems, which can be attributed to faster processors and better communication technologies. A distributed operating system requires distributed algorithms to provide basic operating system functionality like mutual exclusion, deadlock detection, etc. A number of such algorithms have been proposed in the literature. Traditionally, these distributed algorithms have been presented in a theoretical way, with limited attempts to simulate actual working models. This paper discusses our experience in simulating distributed algorithms with the aid of some existing tools, including OPNET and Xplot. We discuss our efforts to define a basic model‐based framework for rapid simulation and visualization, and illustrate how we used this framework to evaluate some classic algorithms. We have also shown how the performance of different algorithms can be compared based on some collected statistics. To keep the focus of this paper on the approach itself, and our experience with tool integration, we only discuss some relatively simple models. Yet, the approach can be applied to more complex algorithm specifications. Copyright © 2001 John Wiley & Sons, Ltd.     

并发操作系统中基于有色Petri网的死锁检测与避免

1.引言系统的并发性与资源的共享性是并发操作系统的主要特征,其目的是最大限度地提高计算机资源的利用率。死锁是并发操作系统必须解决的一个重要问题。人们试图用不同的方法来解决死锁问题。如Dijkstra提出的有名的死锁避免的“银行家算法”,Coffman等人给出的死锁检测算法。 Petri网模型作为模拟与分析并发、异步、分布式系统的一种有效工具,已被用于解决操作系统中的许多问题。如进程通讯中的生产者/消费者问题、哲学家用餐问题,资源竞     

Fast, centralized detection and resolution of distributed deadlocks in the generalized model

In the literature, only a few studies have been performed on the distributed deadlock detection and resolution problem in the generalized request model. Most of the studies are based on the diffusing computation technique where propagation of probes and backward propagation of replies are required to detect deadlock. The replies carry the dependency information between processes for the initiator of the algorithm to determine deadlock. Since fast detection of deadlock is critical, we take a centralized approach that removes the need of backward propagation of replies, but sends the dependency information directly to the initiator of the algorithm. This enables reduction of time cost for deadlock detection to half of that of the existing distributed algorithms. The algorithm is extended to handle concurrent executions in order to further improve deadlock detection time, whereas the current algorithms focus only on a single execution. Simulation experiments are performed to see the effectiveness of this centralized approach as compared to previous distributed algorithms. It is found that our algorithm shows better results in several performance metrics especially in deadlock latency and algorithm execution time.     

分布式系统死锁的预防、避免和检测

分布式系统涉及到资源和数据的高度共享,从而可能引发死锁。分布式系统的死锁是由于资源和通讯产生的。从分布式系统死锁产生的条件,解决策略,以及分布式系统中死锁预防、避免和检测的各种算法进行了具体阐述。     

Performance analysis of distributed deadlock detection algorithms

The paper presents a probabilistic performance analysis of a deadlock detection algorithm in distributed systems. Although there has been extensive study on deadlock detection algorithms in distributed systems, little attention has been paid to the study of the performance of these algorithms. Most work on performance study has been achieved through simulation but not through an analytic model. Min (1990), to the best of our knowledge, made the sole attempt to evaluate the performance of distributed deadlock detection algorithms analytically. Being different from Min's, our analytic approach takes the time-dependent behavior of each process into consideration rather than simply taking the mean-value estimation. Furthermore, the relation among the times when deadlocked processes become blocked is studied, which enhances the accuracy of the analysis. We measure performance metrics such as duration of deadlock, the number of algorithm invocations, and the mean waiting time of a blocked process. It is shown that the analytic estimates are nearly consistent with simulation results     

Deadlock free routing algorithms for irregular mesh topology NoC systems with rectangular regions

The simplicity of regular mesh topology Network on Chip (NoC) architecture leads to reductions in design time and manufacturing cost. A weakness of the regular shaped architecture is its inability to efficiently support cores of different sizes. A proposed way in literature to deal with this is to utilize the region concept, which helps to accommodate cores larger than the tile size in mesh topology NoC architectures. Region concept offers many new opportunities for NoC design, as well as provides new design issues and challenges. One of the most important among these is the design of an efficient deadlock free routing algorithm. Available adaptive routing algorithms developed for regular mesh topology cannot ensure freedom from deadlocks. In this paper, we list and discuss many new design issues which need to be handled for designing NoC systems incorporating cores larger than the tile size. We also present and compare two deadlock free routing algorithms for mesh topology NoC with regions. The idea of the first algorithm is borrowed from the area of fault tolerant networks, where a network topology is rendered irregular due to faults in routers or links, and is adapted for the new context. We compare this with an algorithm designed using a methodology for design of application specific routing algorithms for communication networks. The application specific routing algorithm tries to maximize adaptivity by using static and dynamic communication requirements of the application. Our study shows that the application specific routing algorithm not only provides much higher adaptivity, but also superior performance as compared to the other algorithm in all traffic cases. But this higher performance for the second algorithm comes at a higher area cost for implementing network routers.     

A Simulation Study on Distributed Mutual Exclusion

In the problem of mutual exclusion, concurrent access to a shared resource using a structural program abstraction called acritical section(CS) must be synchronized such that at any time only one process can enter the CS. In a distributed system, due to the lack of both a shared memory and a global clock, and due to unpredictable message delay, the design of a distributed mutual exclusion algorithm that is free from deadlock and starvation is much more complex than that in a centralized system. Based on different assumptions about communication topologies and a widely varying amount of information maintained by each site about other sites, several distributed mutual exclusion algorithms have been proposed. In this paper, we suvrey and analyze several well-known distributed mutual exclusion algorithms according to their related characteristics. We also compare the performance of these algorithms by a simulation study. Finally, we present a comparative analysis of these algorithms.     

Robustness of deadlock avoidance algorithms for sequential processes

Although deadlock avoidance issue has attracted much attention and has been extensively studied, most of the existing results assume reliable machines. This assumption makes it difficult to apply existing deadlock avoidance algorithms to real manufacturing systems with unreliable machines. This paper presents the results to apply an existing deadlock avoidance algorithm to systems with unreliable machines by analyzing the robustness of the deadlock avoidance algorithm. Sequential production processes are considered in this paper, and Petri Net is adopted as the tool for modeling and analysis of the sequential processes. Different types of tolerable machine failures under which liveness property can be preserved are characterized. Computational complexity of the proposed algorithm is analyzed.     

Mobile agent-enabled framework for structuring and building distributed systems on the internet

Mobile agent has shown its promise as a powerful means to complement and enhance existing technology in various application areas. In particular, existing work has demonstrated that MA can simplify the development and improve the performance of certain classes of distributed applications, especially for those running on a wide-area, heterogeneous, and dynamic networking environment like the Internet. In our previous work, we extended the application of MA to the design of distributed control functions, which require the maintenance of logical relationship among and/or coordination of proc- essing entities in a distributed system. A novel framework is presented for structuring and building distributed systems, which use cooperating mobile agents as an aid to carry out coordination and cooperation tasks in distributed systems. The framework has been used for designing various distributed control functions such as load balancing and mutual ex- clusion in our previous work. In this paper, we use the framework to propose a novel ap- proach to detecting deadlocks in distributed system by using mobile agents, which dem- onstrates the advantage of being adaptive and flexible of mobile agents. We first describe the MAEDD (Mobile Agent Enabled Deadlock Detection) scheme, in which mobile agents are dispatched to collect and analyze deadlock information distributed across the network sites and, based on the analysis, to detect and resolve deadlocks. Then the design of an adaptive hybrid algorithm derived from the framework is presented. The algorithm can dynamically adapt itself to the changes in system state by using different deadlock detec- tion strategies. The performance of the proposed algorithm has been evaluated using simulations. The results show that the algorithm can outperform existing algorithms that use a fixed deadlock detection strategy.     

On a simple deadlock recovery problem

In this note a polynomial time algorithm is given for the minimum cost recovery from a deadlock situation resulting from a new request by a single task in a deadlock free system of tasks. We obtain the algorithm by reducing this deadlock recovery problem to a particular network flow problem.     

A deadlock recovery strategy for unified automated material handling systems in 300 mm wafer fabrications

A key issue emerging from the unified automated material handling systems (UAMHSs) in 300 mm wafer fabrications is the system deadlock. This paper addresses the deadlock recovery strategy of unified automated material handling systems (UAMHSs) with limited buffers. A formal model for UAMHSs deadlock detection is proposed. Sufficient conditions for system deadlocks based on actual UAMHS characteristics are defined along with a novel deadlock recovery strategy. Moreover, an effective heuristic algorithm is proposed for parallel resolving UAMHS deadlocks. The performances are evaluated in simulation by monitoring indexes reflecting efficiency of the material handling system. Results of the simulation experiments show that the novel deadlock recovery strategy is superior to the benchmark strategy in reducing deadlock time and improving tools’ utilization. Furthermore, the proposed algorithm features real-time operation and large scale cases, and is suitable for practical applications.     

虚网叠加构造自适应路由算法的有效框架

大规模并行处理机系统中路由算法对互联网络通信性能和系统性起着重要作用。     

Efficient detection and resolution of OR deadlocks in distributed systems

This paper proposes a distributed algorithm for resolving deadlocks under the OR request model. The algorithm builds a distributed spanning tree by propagating probes. An encoding scheme is devised to deduce the ancestor–descendant relationship between tree nodes, so that the initiator of the algorithm collects only non-tree edge information to detect deadlock, whereas the current algorithms require all the edge information for deadlock detection. The proposed algorithm resolves all deadlocks reachable from the initiator. Its performance in terms of number of messages and execution time is better than or comparable to that of the existing algorithms. We further showed through analytic evaluation that the suggested algorithm substantially shortens deadlock detection time.