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DETECTING CAUSAL RELATIONSHIPS IN distributed COMPUTATIONS - IN SEARCH OF THE HOLY-GRAIL

distributed COMPUTING 1994年第3期7卷 149-174页

作者： SCHWARZ, R MATTERN, F UNIV SAARLAND DEPT COMP SCI D-66041 SAARBRUCKEN GERMANY

The paper shows that characterizing the causal relationship between significant events is an important but non-trivial aspect for understanding the behavior of distributed programs. An introduction to the notion of causality and its relation to logical time is given;some fundamental results concerning the characterization of causality are presented. Recent work on the detection of causal relationships in distributed computations is surveyed. The issue of observing distributed computations in a causally consistent way and the basic problems of detecting global predicates are discussed. To illustrate the major difficulties, some typical monitoring and debugging approaches are assessed, and it is demonstrated how their feasibility is severely limited by the fundamental problem to master the complexity of causal relationships.

关键词： distributed computation Causality distributed system Causal ordering Logical time Vector time Global predicate detection distributed debugging Timestamps

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Detection of summative global predicates

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IEICE TRANSACTIONS ON INFORMATION AND SYSTEMS 2003年第5期E86D卷 976-980页

作者： Chen, LB Wu, IC Chin Min Coll Dept Comp Sci & Informat Engn Fac Maio Li Taiwan Natl Chiao Tung Univ Dept Comp Sci & Informat Engn Fac Hsinchu Taiwan

In many distributed systems, tokens are fundamental tools to manage resources shared by processes. Thus, monitoring tokens has become a significant problem in developing the distributed programs. This paper formulates the problems of monitoring tokens in terms of detecting the special global predicates, called summative global predicates. In this paper, several algorithms to detect various summative global predicates are developed and their time complexities are discussed.

关键词： distributed debugging distributed system global predicate minimum global snapshot

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Using Weaker Consistency Models with Monitoring and Recovery for Improving Performance of Key-Value Stores 8

Using Weaker Consistency Models with Monitoring and Recovery...

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8th Latin-American Symposium on Dependable Computing (LADC)

作者： Duong Nguyen Charapko, Aleksey Kulkarni, Sandeep S. Demirbas, Murat Michigan State Univ E Lansing MI 48824 USA SUNY Buffalo Buffalo NY USA

ISBN: (纸本)9781538684894

Limitations of the CAP theorem imply that if availability is desired in the presence of faults - especially that create network partitions (or substantial delays), one must sacrifice sequential consistency, a consistency model that is more natural for system design. We focus on the problem of what a designer should do if he/she has an algorithm that works correctly with sequential consistency but is faced with an underlying key-value store that provides a weaker (e.g., eventual or causal) consistency. We propose a detect-rollback based approach: The designer identifies a correctness predicate, say P, and continues to run the protocol, as our system monitors P. If P is violated (because the underlying key-value store provides a weaker consistency), the system rolls back and resumes the computation at a state where P holds. We evaluate this approach with practical graph applications running on the Voldemort key-value store. Our experiments, deployed on Amazon AWS EC2 instances, show that using eventual consistency with monitoring can provide a 50-80% increase in throughput when compared with sequential consistency. We also show that the overhead of the monitoring itself is low (typically less than 4%) and the latency of detecting violations is small. In particular, more than 99.9% of violations are detected in less than 50 milliseconds in regional AWS networks, and in less than 5 seconds in global AWS networks. In turn, this makes it possible to provide efficient recovery from such faults with a minimal amount of work wasted due to rollbacks.

关键词： predicate detection distributed debugging distributed monitoring distributed snapshot distributed key-value stores

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Clairvoyant: A Comprehensive Source-Level Debugger for Wireless Sensor Networks 07

Clairvoyant: A Comprehensive Source-Level Debugger for Wirel...

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5th ACM Conference on Embedded Networked Sensor Systems

作者： Yang, Jing Soffa, Mary Lou Selavo, Leo Whitehouse, Kamin Univ Virginia Dept Comp Sci Charlottesville VA 22903 USA

ISBN: (纸本)9781595937636

Wireless sensor network (WSN) applications are notoriously difficult to develop and debug. This paper describes Clairvoyant which is a comprehensive source-level debugger for wireless, embedded networks. With Clairvoyant, a developer can wirelessly connect to a sensor network and execute standard debugging commands including break, step, watch, and back-trace, as well as new commands that are specially designed for debugging WSNs. Clairvoyant attempts to minimize its effect on the program being debugged in terms of network load, memory footprint, execution speed, clock consistency, and flash lifetime.

关键词： Source-Level debugging distributed debugging Embedded debugging Wireless Sensor Networks

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Diagnosing distributed Systems with Self-propelled Instrumentation

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9th International Middleware Conference

作者： Mirgorodskiy, Alexander V. Miller, Barton P. VMware Inc. Computer Sciences Dept. University of Wisconsin

ISBN: (纸本)9783540898559

We present a three-part approach for diagnosing bugs and performance problems in production distributed environments. First, we introduce a novel execution monitoring technique that dynamically injects a fragment of code, the agent, into an application process on demand. The agent inserts instrumentation ahead of the control flow within the process and propagates into other processes, following communication events, crossing host boundaries, and collecting a distributed function-level trace of the execution. Second, we present an algorithm that separates the trace into user-meaningful activities called flows. This step simplifies manual examination and enables automated analysis of the trace. Finally, we describe our automated root cause analysis technique that compares the flows to help the analyst locate an anomalous flow and identify a function in that flow that is a likely cause of the anomaly. We demonstrate the effectiveness of our techniques by diagnosing two complex problems in the Condor distributed scheduling system.

关键词： distributed debugging performance analysis dynamic instrumentation trace analysis anomaly detection

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Identifying Useless States in Non-FIFO distributed Computations by using Pseudo Timestamps

Identifying Useless States in Non-FIFO Distributed Computati...

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10th International Symposium on Pervasive Systems, Algorithms, and Networks

作者： Chen, Lung-Pin Ho, Meng-Yuan Hong, Jhen-You Tunghai Univ Dept Comp Sci & Informat Engn Taichung 40704 Taiwan

ISBN: (纸本)9781424454037

In a distributed system, a monitor process collects the execution states and invokes a detection procedure to test and debug the program. This paper investigates the global state analyzing problems for the non-FIFO distributed environments. In this paper, the states unknown to the monitor process are represented by using the pseudo states. Based on this technique, this paper develops an algorithm capable of identifying the maximum number of useless states for the programs run in an non-FIFO distributed environment.

关键词： distributed debugging distributed program Global predicate Global state Timestamp

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MPIWIZ: Subgroup Reproducible Replay of MPI Applications

MPIWIZ: Subgroup Reproducible Replay of MPI Applications

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14th ACM SIGPLAN Symposium on Principles and Practice of Parallel Programming

作者： Xue, Ruini Liu, Xuezheng Wu, Ming Guo, Zhenyu Chen, Wenguang Zheng, Weimin Zhang, Zheng Voelker, Geoffrey M. Tsinghua Univ Beijing Peoples R China Univ Calif San Diego San Diego CA 92103 USA

ISBN: (纸本)9781605583976

Message Passing Interface (MPI) is a widely used standard for managing coarse-grained concurrency on distributed computers. debugging parallel MPI applications, however, has always been a particularly challenging task due to their high degree of concurrent execution and non-deterministic behavior. Deterministic replay is a potentially powerful technique for addressing these challenges, with existing MPI replay tools adopting either data-replay or order-replay approaches. Unfortunately, each approach has its tradeoffs. Data-replay generates substantial log sizes by recording every communication message. Order-replay generates small logs, but requires all processes to be replayed together. We believe that these drawbacks are the primary reasons that inhibit the wide adoption of deterministic replay as the critical enabler of cyclic debugging of MPI applications. This paper describes subgroup reproducible replay (SRR), a hybrid deterministic replay method that provides the benefits of both data-replay and order-replay while balancing their trade-offs. SRR divides all processes into disjoint groups. It records the contents of messages crossing group boundaries as in data-replay, but records just message orderings for communication within a group as in order-replay. In this way, SRR can exploit the communication locality of traffic patterns in MPI applications. During replay, developers can then replay each group individually. SRR reduces recording overhead by not recording intra-group communication, and reduces replay overhead by limiting the size of each replay group. Exposing these tradeoffs gives the user the necessary control for making deterministic replay practical for MPI applications. We have implemented a prototype, MPIWIZ, to demonstrate and evaluate SRR. MPIWIZ employs a replay framework that allows transparent binary instrumentation of both library and system calls. As a result, MPIWIZ replays MPI applications with no source code modification and relinking,

关键词： Reliability Design Performance non-determinism Message Passing Interface record and replay distributed debugging

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Checking global properties for local computations in graphs with applications to invariant testing

Checking global properties for local computations in graphs ...

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5th Mexican International Conference in Computer Science (ENC 2004)

作者： Mosbah, M Ossamy, R Univ Bordeaux 1 ENSEIRB LaBRI F-33405 Talence France

ISBN: (纸本)0769521606

Global predicates in distributed systems are predicates considering the state of more than one process. They are a useful concept for debugging parallel programs, e.g., for specifying assertions, breakpoints or termination. In this paper we propose an algorithm for detecting the validity of local and global state predicates in distributed algorithms encoded by means of local computations. This algorithm is based on ideas introduced by Cooper and Marzullo and on the approach of Garg and Waldecker. It uses the Lamport's happened-before ordering relationship to construct a partial sorted sequence of all the events that have changed the local state of any process during a computation. While the sequence is traversed, all the global states through which the system has passed are computed and the validity of the given properties is checked. Under the same assumptions, our algorithm is significantly more efficient than the algorithms by Cooper and Marzullo and by Garg and Waldecker.

关键词： global predicates detection consistent global states local computations distributed systems distributed programming languages distributed debugging

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Demo abstract: Effective source-level debugging of wireless sensor networks

Demo abstract: Effective source-level debugging of wireless ...

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5th ACM International Conference on Embedded Networked Sensor Systems, SenSys'07

作者： Yang, Jing Soffa, Mary Lou Whitehouse, Kamin Department of Computer Science University of Virginia United States

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distributed simulations: issues and implementations in a cluster of workstations environment

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COMPUTER SYSTEMS SCIENCE AND ENGINEERING 1999年第1期14卷 27-37页

作者： Meng, XN Univ Texas Pan Amer Dept Comp Sci Edinburg TX 78539 USA

We investigate in this paper various issues in parallel and distributed simulations in general, and its implementation in cluster of workstation environment in particular. The first part of the paper surveys the filed of parallel and distributed simulations, describes the issues that many researchers have been tackling. The second part of the paper presents the research projects carried out by the author in three areas, state saving in distributed simulations, implementing and performance issues in cluster of workstations, and debugging in distributed simulation environment. Our research found that the memory requirement of state saving can be reduced in certain types of distributed simulations;while decreasing communications among participating processes may reduce the cost of communications, it may result in more rollbacks because the loss of synchronization;debugging distributed programs is difficult, but it can be aided using library functions we developed.

关键词： distributed simulations distributed computing distributed debugging communications

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