this paper sketches our experience withthe design and implementation of a parallel object-oriented language and its distributed run-time system. the language integrates two original mechanisms for concurrency control...
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ISBN:
(纸本)0818658401
this paper sketches our experience withthe design and implementation of a parallel object-oriented language and its distributed run-time system. the language integrates two original mechanisms for concurrency control: a synchronization mechanism that does not interfere with inheritance nor with subtyping, and a mechanism that serves for managing object groups. Because of the increasing power of inter-connection networks, the language's run-time system has been designed for a distributed architecture instead of a single multiprocessor machine. Furthermore, in order to ease the development of correct applications, we have chosen to rely on the run-time system to provide the required efficiency instead of offering the programmer low level primitives to be used for producing efficient code.
In distributed environments, entities are distributed among different security domains and they do not have prior knowledge of one another. In this setting, distributedsystems and their security components such as en...
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ISBN:
(纸本)9781509049066
In distributed environments, entities are distributed among different security domains and they do not have prior knowledge of one another. In this setting, distributedsystems and their security components such as entities, certificates, credentials, policies and trust values are dynamic and constantly changing. thus, access control models and trust approaches are necessary to support the dynamic and distributed features of such systems and their components. the objective of this paper is to present a comprehensive survey about the security research in distributedsystems. We have reviewed the dynamic and distributed nature of the components and evaluation methods of major authorization systems and access control models in existing literature. Based on this overview, we present a survey of selected trust schemes. We provide a categorization for recommendation-based and reputation-based trust models based on trust evaluation. Additionally, we use credential or certificate storage and chain discovery methods for categorizing evidence based and policy-based trust models. this work can be used as a reference guide to understand authorization and trust management and to further research fully decentralized and distributed authorization systems.
this paper introduces optimistic lock synchronization using the group write consistency model (GWC). GWC guarantees strict ordering of all shared writes in a processor group. In optimistic synchronization, if a lock-r...
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ISBN:
(纸本)0818658401
this paper introduces optimistic lock synchronization using the group write consistency model (GWC). GWC guarantees strict ordering of all shared writes in a processor group. In optimistic synchronization, if a lock-requesting processor can assume that the lock is free, execution of mutually exclusive code starts immediately. Wrong assumption results in rollback. Shared variable updates remain in the group until the lock manager grants the lock to the requesting processor. By evaluating the time needed for three processors to execute mutually exclusive code, GWC can out-perform weak, release, and even entry consistency. Simulations of task management using exclusive access to a shared queue, also show much faster mutual exclusion with GWC. Optimistic mutual exclusion may further halve total delays in accessing shared resources.
the Monte-Carlo method (stochastic simulation) is the one of the major tools in statistical physics, complex systems science and many other fields and is considered to be the promising computational scheme to run on n...
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ISBN:
(纸本)9780769547497
the Monte-Carlo method (stochastic simulation) is the one of the major tools in statistical physics, complex systems science and many other fields and is considered to be the promising computational scheme to run on nearest future exaflop supercomputers with many thousands and even millions of computational cores. We suggest a technique of the distributed stochastic simulation suitable for running on large amount of computational cores of the supercomputer. An example of the highly scalable application utilizing distributed stochastic simulation on up-to-date tera- and petaflop supercomputers is the program library PARMONC. thorough examination of the proposed technique was done using simulation model that is based on the multiagent simulation system AGNES. the AGNES in particular enables one to evaluate the performance of the supposed exaflop supercomputer loaded withthe distributed stochastic simulation.
In this paper, a novel workflow-aware distributed versioning file system, WAD-VFS is presented to overcome the shortcoming of traditional DFS and facilitate the high performance computing. Our preliminary simulation r...
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ISBN:
(纸本)0780390377
In this paper, a novel workflow-aware distributed versioning file system, WAD-VFS is presented to overcome the shortcoming of traditional DFS and facilitate the high performance computing. Our preliminary simulation results are impressive and can hence serve as a supporting evidence of deploying WAD-VFS to our ongoing metacomputing project, Trellis system.
Reliability is one of the important issues in the design of distributedcomputingsystems (DCSs). this paper deals withthe problem of task allocation in heterogeneous DCSs for maximizing system reliability with sever...
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ISBN:
(纸本)9780769547497
Reliability is one of the important issues in the design of distributedcomputingsystems (DCSs). this paper deals withthe problem of task allocation in heterogeneous DCSs for maximizing system reliability with several resource constraints. Memory capacity, processing load and communication rate are major constraints in the problem. Reliability oriented task allocation problem is NP-hard, thus many algorithms were presented to find a near optimal solution. this paper presents a Hybrid of Simulated Annealing and Tabu Search (HSATS) that uses a non-monotonic cooling schedule to find a near optimal solution within reasonable time. the HSATS algorithm was implemented and evaluated through experimental studies on a large number of randomly generated instances. Results have shown that the algorithm can obtain optimal solution in most cases. When it fails to produce optimal solution, deviation is less than 0.2 percent. therefore in terms of solution quality, HSATS is significantly better than pure Simulated Annealing.
Next-generation computation-intensive applications in various fields of science and engineering feature large-scale computing workflows with complex structures that are often modeled as directed acyclic graphs. Suppor...
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ISBN:
(纸本)9780769534343
Next-generation computation-intensive applications in various fields of science and engineering feature large-scale computing workflows with complex structures that are often modeled as directed acyclic graphs. Supporting such task graphs and optimizing their end-to-end network performances in heterogeneous computing environments are critical to the success of these distributed applications that require fast response. We construct analytical models for computing modules, network nodes, and communication links to estimate data processing and transport overhead, and formulate the task graph mapping with node reuse and resource sharing for minimum end-to-end delay as an NP-complete optimization problem. We propose a heuristic approach to this problem that recursively computes and maps the critical path to the network using a dynamic programming-based procedure. the performance superiority of the proposed approach is justified by an extensive set of experiments on simulated data sets in comparison with existing methods.
Event based debuggers for distributedsystems automatically detect occurrences of user specified events. During debugging it is not always possible to breakpoint a computation in a state that reflects an event occurre...
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ISBN:
(纸本)0818658401
Event based debuggers for distributedsystems automatically detect occurrences of user specified events. During debugging it is not always possible to breakpoint a computation in a state that reflects an event occurrence. thus, to avoid unnecessary breakpoints we must develop techniques that determine, prior to the initiation of a breakpoint, whether an event occurrence will be captured by the breakpoint. In this paper we propose the simultaneity operator for achieving the above goal. this operator asserts that its operand events, which correspond to states of different processes in the distributed computation, are all true at a point in the program and stable with respect to this point. the stability of events guarantees that the initiation of a breakpoint at this point will leave the system in a state which reflects the event occurrence. We present static analysis techniques that identify points in a program at which user specified simultaneous events should be evaluated to avoid unnecessary breakpointing. the statically computed information also enables minimal instrumentation of the program for the detection of event occurrences.
distributed diffusion is a powerful algorithm for multi-task state estimation which enables networked agents to interact with neighbors to process input data and diffuse information across the network. Compared to a c...
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ISBN:
(纸本)9781538654705
distributed diffusion is a powerful algorithm for multi-task state estimation which enables networked agents to interact with neighbors to process input data and diffuse information across the network. Compared to a centralized approach, diffusion offers multiple advantages that include robustness to node and link failures. In this paper, we consider distributed diffusion for multi-task estimation where networked agents must estimate distinct but correlated states of interest by processing streaming data. By exploiting the adaptive weights used for diffusing information, we develop attack models that drive normal agents to converge to states selected by the attacker. the attack models can be used for both stationary and non-stationary state estimation. In addition, we develop a resilient distributed diffusion algorithm under the assumption that the number of compromised nodes in the neighborhood of each normal node is bounded by F and we show that resilience may be obtained at the cost of performance degradation. Finally, we evaluate the proposed attack models and resilient distributed diffusion algorithm using stationary and non-stationary multi-target localization.
We develop a framework that helps in developing understanding of a fault-tolerant distributed system and so helps in designing such systems. We define a unit of computation in such systems, referred to as a molecule, ...
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ISBN:
(纸本)0818658401
We develop a framework that helps in developing understanding of a fault-tolerant distributed system and so helps in designing such systems. We define a unit of computation in such systems, referred to as a molecule, that has a well defined interface with other molecules, i.e. has minimal dependence on other molecules. the smallest such unit - an indivisible molecule - is termed as an atom. We show that any execution of a fault-tolerant distributed computation can be seen as an execution of molecules/atoms in a partial order, and such a view provides insights into understanding the computation, particularly for a fault-tolerant system where it is important to guarantee that a unit of computation is either completely executed or not at all and system designers need to reason about the states after execution of such units. We prove different properties satisfied by molecules and atoms, and present algorithms to detect atoms in an ongoing computation and to force the completion of a molecule. We illustrate the uses of the developed work in application areas such as debugging, checkpointing, and reasoning about stable properties.
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