MPI-RCDD: A Framework for MPI Runtime Communication Deadlock Detection

The message passing interface (MPI) has become a de facto standard for programming models of highperformance computing, but its rich and flexible interface semantics makes the program easy to generate communication deadlock, which seriously affects the usability of the system. However, the existing detection tools for MPI communication deadlock are not scalable enough to adapt to the continuous expansion of system scale. In this context, we propose a framework for MPI runtime communication deadlock detection, namely MPI-RCDD, which contains three kinds of main mechanisms. Firstly, MPI-RCDD has a message logging protocol that is associated with deadlock detection to ensure that the communication messages required for deadlock analysis are not lost. Secondly, it uses the asynchronous processing thread provided by the MPI to implement the transfer of dependencies between processes, so that multiple processes can participate in deadlock detection simultaneously, thus alleviating the performance bottleneck problem of centralized analysis. In addition, it uses an AND⊕OR model based algorithm named AODA to perform deadlock analysis work. The AODA algorithm combines the advantages of both timeout-based and dependency-based deadlock analysis approaches, and allows the processes in the timeout state to search for a deadlock circle or knot in the process of dependency transfer. Further, the AODA algorithm cannot lead to false positives and can represent the source of the deadlock accurately. The experimental results on typical MPI communication deadlock benchmarks such as Umpire Test Suit demonstrate the capability of MPIRCDD. Additionally, the experiments on the NPB benchmarks obtain the satisfying performance cost, which show that the MPI-RCDD has strong scalability.     

Framework for distributed video surveillance in heterogeneous environment

In order to overcome the disadvantages of traditional centralized video monitoring system or distributed systems based on wired network, we propose a framework for distributed video surveillance in heterogeneous environment. Video flows are compressed with the scalable video encoding standard MPEG-4 and transmitted over lnternet or wireless network. Video surveillance can be performed wherever there is Internet or mobile telephone signal. The feasibility of this framework has been demonstrated with a prototype implementation. The system is cheaper and easier to achieve with simple equipments, so it can be widely used in practice.     

A multiagent dynamic interaction testbed: Theoretic framework, system architecture and experimentation

Recent research on Distributed Artificial Intelligence(DAI)has focused upon agents‘ interaction in Multiagent System.sThis paper presents a text understanding oriented multiagent dynamic interaction testbed(TUMIT);the theoretic framework based upon game theory,the free-market-like system marchitecture,and experimentation on TUMIT.Unlike other DAI testbeds,TUMIT views different text understanding(TU)methods as different“computational resources”,and makes agents choose different TU paths and computational resources according to the resouce information on the bulletins in their hostcomputer.Therefore,in TUMIT,task allocation is wholly distributed.This makes TUMIT work like a “free market”.In such a system,agents‘choices and resource load may oscillate.It is shown theoretically and experimentally that if agents use multi-level of “history information”,their behavior will tend to converge to a Nash equilibrium situation;and that if agents use “fecall-forget” strategy on “history information”,the convergence can be accelerated and the agents can acclimate themselves to changed environment.Compared with other DAI testbeds,TUMIT is more distributed,and the agents in TUMIT are more adaptive to the dynamic environment.     

MADIDS：一种基于移动代理的新型分布式入侵检测系统

When traditional Intrusion Detection System(IDS)is used to detect and analyze the great flow data transfer in high-speed network,it usually causes the computation bottleneck.This paper presents a new Mobile Agent Distributed IDS(MADIDS) system based on the mobile agents.This system is specifically designed to process the great flow data transfer in high-speed network.In MADIDS,the agents that are set at each node process the data transfer by distributed computation architecture.Meanwhile by using the reconfiguration quality of the mobile agents,the load balance of distributed computation can be dynamically implemented to gain the high-performance computing ability.This ability makes the detecting and analyzing of high-speed network possible.MADIDS can effectively solve the detection and analysis performance bottleneck caused by the great flow data transfer in high-speed network.It enhances the performance of IDS in high-speed network.In this paper,we construct the infrastructure and theoretical model of MADIDS,and the deficiencies of MADIDS and future research work are also indicated.     

A mobile-agent-based approach to software coordination in the HOOPE system

Software coordination is central to the construction of large-scale high-performance distributed applications with software services scattered over the decentralized Internet. In this paper, a new mobile-agent-based architecture is proposed for the utilization and coordination of geographically distributed computing resources. Under this architecture, a user application is built with a set of software agents that can travel across the network autonomously. These agents utilize the distributed resources and coordinate with each other to complete their task. This approach' s advantages include the natural expression and flexible deployment of the coordination logic, the dynamic adaptation to the network environment and the potential of better application performance. This coordination architecture, together with an object-oriented hierarchical parallel application framework and a graphical application construction tool, is implemented in the HOOPE environment, which provides a systematic support for the de     

A distributed algorithm for multi-region problem in BEM

The situation of multi-region problem may oftem appear when boundary element method(BEM)is applied in practical problems especially in VLSI-CAD.It is difficult to deal with this problem if traditional methods are used.Particularly. when the problem to be solved contains a lot of materials,the advantages of using BEM such as simplicity,convenience and rapidity will be weakened due to the complexity of solving complex boundary element equation.In this paper a distributed algorithm for multi-region problem in BEM is presented.This algorithm has been implemented in a distributed system consisting of 3 workstations to extract VLSI layout parameters.The results show that the calculation time of this distributed algorithm is less than that of the traditional methods.The results also demonstrate that this algorithm can speed up the computation and has the features of parallelism and high efficiency.     

Distributed multi-agent temporal-difference learning with full neighbor information

This paper presents a novel distributed multi-agent temporal-difference learning framework for value function approximation, which allows agents using all the neighbor information instead of the information from only one neighbor. With full neighbor information, the proposed framework (1) has a faster convergence rate, and (2) is more robust compared to the state-of-the-art approaches. Then we propose a distributed multi-agent discounted temporal difference algorithm and a distributed multi-agent average cost temporal difference learning algorithm based on the framework. Moreover, the two proposed algorithms’ theoretical convergence proofs are provided. Numerical simulation results show that our proposed algorithms are superior to the gossip-based algorithm in convergence speed, robustness to noise and time-varying network topology.     

Evaluation of Program Code Caching for Mobile Agent Migrations

Mobile agents are able to migrate among machines to achieve their tasks. This feature is attractive to design, implement, and maintain distributed systems because we can implement both client-side and server-side programming in one mobile agent. However, it involves the increase of data traffic for mobile agent migrations. In this paper, we propose program code caching to reduce the data traffic caused by mobile agent migrations. A mobile agent consists of many program codes that define a task executed in each machine they migrate; thus, the mobile agent migration involves the transfer of their program codes. Therefore, our method reduces the number of the transfer of program codes by using program code cache. We have implemented our method on a mobile agent framework called Maglog and conducted experiments on a meeting scheduling system.     

Distributed robust MPC for nonholonomic robots with obstacle and collision avoidance

Considering that the inevitable disturbances and coupled constraints pose an ongoing challenge to distributed control algorithms, this paper proposes a distributed robust model predictive control (MPC) algorithm for a multi-agent system with additive external disturbances and obstacle and collision avoidance constraints. In particular, all the agents are allowed to solve optimization problems simultaneously at each time step to obtain their control inputs, and the obstacle and collision avoidance are accomplished in the context of full-dimensional controlled objects and obstacles. To achieve the collision avoidance between agents in the distributed framework, an assumed state trajectory is introduced for each agent which is transmitted to its neighbors to construct the polyhedral over-approximations of it. Then the polyhedral over-approximations of the agent and the obstacles are used to smoothly reformulate the original nonconvex obstacle and collision avoidance constraints. And a compatibility constraint is designed to restrict the deviation between the predicted and assumed trajectories. Moreover, recursive feasibility of each local MPC optimization problem with all these constraints derived and input-to-state stability of the closed-loop system can be ensured through a sufficient condition on controller parameters. Finally, simulations with four agents and two obstacles demonstrate the efficiency of the proposed algorithm.     

Structure-Based Deadlock Checking of Asynchronous Circuits

It is important to verify the absence of deadlocks in asynchronous circuits. Much previous work relies on a reachability analysis of the circuits’ states, with the use of binary decision diagrams (BDDs) or Petri nets to model the behaviors of circuits. This paper presents an alternative approach focusing on the structural properties of well-formed asynchronous circuits that will never suffer deadlocks. A class of data-driven asynchronous pipelines is targeted in this paper, which can be viewed as a network of basic components connected by handshake channels. The sufficient and necessary conditions for a component network consisting of Steer, Merge, Fork and Join are given. The slack elasticity of the channels is analyzed in order to introduce pipelining. As an application, a deadlock checking method is implemented in a syntax-directed asynchronous design tool -- Teak. The proposed method shows a great runtime advantage when compared against previous Petri net based verification tools.     

A one-phase algorithm to detect distributed deadlocks in replicateddatabases

Replicated databases that use quorum-consensus algorithms to perform majority voting are prone to deadlocks. Due to the P-out-of-Q nature of quorum requests, deadlocks that arise are generalized deadlocks and are hard to detect. We present an efficient distributed algorithm to detect generalized deadlocks in replicated databases. The algorithm performs reduction of a distributed wait-for-graph (WFG) to determine the existence of a deadlock. If sufficient information to decide the reducibility of a node is not available at that node, the algorithm attempts reduction later in a lazy manner. We prove the correctness of the algorithm. The algorithm has a message complexity of 2e messages and a worst-case time complexity of 2d+2 hops, where e is the number of edges and d is the diameter of the WFG. The algorithm is shown to perform significantly better in both time and message complexity than the best known existing algorithms. We conjecture that this is an optimal algorithm, in time and message complexity, to detect generalized deadlocks if no transaction has complete knowledge of the topology of the WFG or the system and the deadlock detection is to be carried out in a distributed manner     

分布式移动代理系统的异步死锁检测

移动代理技术在为分布式应用提供全新的网络计算方式的同时也产生了传统分布式计算领域所没有的新的交互模式和执行模式。传统分布式计算的处理方法如并发控制和死锁检测方法不再适用于客户和服务提供者都可在网络中随处移动的移动代理系统。通过移动代理来建模长寿事务,并根据移动代理的特点提出了一种异步分布式死锁检测和解除算法。它将事务代理的执行与死锁检测机制分离,用专门的代理负责死锁检测的初始化、检测和消除等工作。死锁的检测通过创建若干检测代理,使其在各个站点间移动来收集资源请求和分配信息,并据此构造全局等待图;通过分析和探测全局等待图中是否存在圈来完成。算法具有独立于网络的拓扑结构,死锁的检测和事务代理的执行异步操作,不对代理的移动性施加任何限制等特点。     

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.     

Detecting and resolving deadlocks in mobile agent systems

Mobile agents environment is a new application paradigm with unique features such as mobility and autonomy. Traditional deadlock detection algorithms in distributed computing systems do not work well in mobile agent systems due to the unique feature property of the mobile agent. Existing deadlock detection and resolution algorithms in mobile agent systems have limitations such as performance inefficiency and duplicate detection/resolution when multiple mobile agents simultaneously detect/resolve the same deadlock. To address these problems, we propose an improved deadlock detection and resolution algorithm that adopts priority-based technique and lazy reaction strategy. The priority-based technique aims to ensure that there is only one instance of deadlock detection and resolution, and it also helps reduce mobile agent movement and data traffic together with the lazy reaction strategy. The liveness and safety properties of the proposed algorithm are proved in this paper. Theoretical analysis and experimental results show that the proposed algorithm provides better performance in terms of agent movement, data traffic, and execution time.     

Execution coordination in mobile agent-based distributed job workflow execution

Mobile agent-based distributed job workflow execution requires the use of execution coordination techniques to ensure that an agent executing a subjob can locate its predecessors’ execution results. This paper describes the classification, implementation, and evaluation of execution coordination techniques in the mobile agent-based distributed job workflow execution system. First, a classification of the existing execution coordination techniques is developed for mobile agent systems. Second, to put the discussion into perspective, our framework for mobile agent-based distributed job workflow execution over the Grid (that is, MCCF: Mobile Code Collaboration Framework) is described. How the existing coordination techniques can be applied in the MCCF is also discussed. Finally, a performance study has been conducted to evaluate three coordination techniques using real and simulated job workflows. The results are presented and discussed in the paper.     

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.     

Invariant-based verification of a distributed deadlock detectionalgorithm

It is argued that most previous proposals for distributed deadlock detection are incorrect because they have used informal/intuitive arguments to prove the correctness of their algorithms. Informal and intuitive arguments are prone to errors because of the highly complex nature of distributed deadlock detection/resolution algorithms. The priority-based probe algorithm for distributed deadlock detection and resolution of A.L. Choudhary et al. (1989) is corrected, and it is formally proven that the modified algorithm is correct (i.e., that it does detect all deadlocks and does not report phantom deadlocks). The proof technique is novel in that the authors first abstract the properties of the deadlock detection and resolution algorithm by invariants, and then show that the invariants imply the desired correctness of the algorithm     

Characterization of deadlocks in k-ary n-cube networks

A spate of deadlock avoidance-based and deadlock recovery-based routing algorithms have been proposed in recent years without full understanding of the likelihood and characteristics of actual deadlocks in interconnection networks. This work models the interrelationships between routing freedom, message blocking, correlated resource dependencies, and deadlock formation. It is empirically shown that increasing routing freedom, as achieved by allowing unrestricted routing over multiple physical and virtual channels, reduces the probability of deadlocks and the likelihood of other types of correlated message blocking that can degrade performance. Moreover, when true fully adaptive routing is used in k-ary n-cube networks with two or more virtual channels (wormhole OF virtual cut-through switched), it is empirically shown that deadlocks are virtually eliminated in networks with n⩾2. These results indicate that deadlocks are very infrequent when the network and routing algorithm inherently provide sufficient routing freedom, thus increasing the viability of deadlock recovery routing strategies     

A Priority Based Distributed Deadlock Detection Algorithm

Deadlock handling is an important component of transaction management in a database system. In this paper, we contribute to the development of techniques for transaction management by presenting an algorithm for detecting deadlocks in a distributed database system. The algorithm uses priorities for transactions to minimize the number of messages initiated for detecting deadlocks. It does not construct any wait-for graph but detects cycles by an edge-chasing method. It does not detect any phantom deadlock (in the absence of failures), and for the resolution of deadlocks it does not need any extra computation. The algorithm also incorporates a post-resolution computation that leaves information characterizing dependence relations of remaining transactions of the deadlock cycle in the system, and this will help in detecting and resolving deadlocks which may arise in the future. An interesting aspect of this algorithm is that it is possible to compute the exact number of messages generated for a given deadlock configuration. The complexity is comparable to the best algorithm reported. We first present a basic algorithm and then extend it to take into account shared and exclusive lock modes, simultaneous acquisition of multiple locks, and nested transactions.     

Probabilistic odd–even: an adaptive wormhole routing algorithm for 2D mesh network-on-chip

Wormhole routing is a popular routing technique used in network-on-chip. It is efficient but susceptible to deadlock, while deadlock will significantly degrade the network performance of NoC. Most existing adaptive wormhole routings avoid deadlock by reducing the degree of adaptiveness and thus sacrificing network performance. In this paper, we address both deadlock and network performance issues jointly, and propose a probabilistic odd–even (POE) routing algorithm that achieves the minimum packet delivery delay. The proposed POE dynamically adjusts the probabilities of constrained turns that may lead to deadlocks according to the current network conditions, and uses an efficient deadlock detection and recovery scheme when a deadlock happens. By adopting constrained turns adaptively to the network status, it not only reduces the frequency of deadlock and allows the network to be swiftly recovered when it occurs, but also greatly improves the degree of adaptiveness to obtain high network performance. Experimental results show that our method achieves a significant performance improvement both in terms of network throughput and average packet latency compared with the existing methods such as XY, odd–even, abacus turn model and fully adaptive routing algorithm while it only has moderate energy consumption.