Hasil untuk "cs.DC"

Virginia Morejón, Ainhoa González Del Campo, Ibon Galparsoro et al.

Abstract With the increase in marine spatial planning efforts the need for robust environmental assessments that account for multiple pressures of human activities on marine ecosystems is more critical than ever. However, Cumulative Effects Assessment (CEA) practice, a requirement of Strategic Environmental Assessment (SEA) of marine spatial plans, remains insufficient. This paper explores the integration of ecosystem-based approaches into SEA stages for holistic environmental assessments of marine spatial plans that prioritize ecological integrity. It also reviews advancements in marine CEA research, focusing on risk-based approaches for assessing cumulative effects, and addresses the existing disconnection between CEA science and environmental assessment practice. Emphasis is placed on improving key SEA stages that are critical to CEA by identifying principles and approaches that systematically and spatially address the interactions of various pressures and ecosystem receptors across the four dimensions (4D) of marine environments to assess cumulative effects risks. This novel approach, presents a holistic framework aimed at enhancing CEA practice within SEA of marine spatial plans, for more sustainable and ecosystem-focused planning outcomes in marine environments.

Jingwen Liu, Mingzhu Yang, Siyi He

Jinghai He, Haoyu Liu, Yuhang Wu et al.

We provide a preliminary study on utilizing GPU (Graphics Processing Unit) to accelerate computation for three simulation optimization tasks with either first-order or second-order algorithms. Compared to the implementation using only CPU (Central Processing Unit), the GPU implementation benefits from computational advantages of parallel processing for large-scale matrices and vectors operations. Numerical experiments demonstrate computational advantages of utilizing GPU implementation in simulation optimization problems, and show that such advantage comparatively further increase as the problem scale increases.

Omkar Patil, Aarya Shirbhate

This report details the development of a networked distributed system named Group Communication System (GCS), implemented in Java to exemplify socket programming and communication protocols. GCS facilitates group-based client-server communication through a command-line interface (CLI), enabling seamless group interaction and management. The project emphasizes fault tolerance, design patterns, and version control system (VCS) utilization. The report offers insights into system architecture, implementation, and practical considerations, providing a comprehensive understanding of distributed systems' technical background and operational aspects.

Zaynab Zahra, Zihao Li, Rosa Filgueira

This paper introduces Laminar, a novel serverless framework based on dispel4py, a parallel stream-based dataflow library. Laminar efficiently manages streaming workflows and components through a dedicated registry, offering a seamless serverless experience. Leveraging large lenguage models, Laminar enhances the framework with semantic code search, code summarization, and code completion. This contribution enhances serverless computing by simplifying the execution of streaming computations, managing data streams more efficiently, and offering a valuable tool for both researchers and practitioners.

Mike Rainey

In this short paper, we explore a new way to refactor a simple but tricky-to-parallelize tree-traversal algorithm to harness multicore parallelism. Crucially, the refactoring draws from some classic techniques from programming-languages research, such as the continuation-passing-style transform and defunctionalization. The algorithm we consider faces a particularly acute granularity-control challenge, owing to the wide range of inputs it has to deal with. Our solution achieves efficiency from heartbeat scheduling, a recent approach to automatic granularity control. We present our solution in a series of individually simple refactoring steps, starting from a high-level, recursive specification of the algorithm. As such, our approach may prove useful as a teaching tool, and perhaps be used for one-off parallelizations, as the technique requires no special compiler support.

Nick Brown, Maurice Jamieson, Joseph K. L. Lee

Funded by the UK ExCALIBUR H\&ES exascale programme, in early 2022 a RISC-V testbed for HPC was stood up to provide free access for scientific software developers to experiment with RISC-V for their workloads. Here we report on successes, challenges, and lessons learnt from this activity with a view to better understanding the suitability of RISC-V for HPC and important areas to focus RISC-V HPC community efforts upon.

Thomas Schlögl, Ulrich Schmid

Existing protocols for byzantine fault tolerant distributed systems usually rely on the correct agents' ability to detect faulty agents and/or to detect the occurrence of some event or action on some correct agent. In this paper, we provide sufficient conditions that allow an agent to infer the appropriate beliefs from its history, and a procedure that allows these conditions to be checked in finite time. Our results thus provide essential stepping stones for developing efficient protocols and proving them correct.

Xiao Li, Eric Chan, Mohsen Lesani

Byzantine quorum systems provide higher throughput than proof-of-work and incur modest energy consumption. Further, their modern incarnations incorporate personalized and heterogeneous trust. Thus, they are emerging as an appealing candidate for global financial infrastructure. However, since their quorums are not uniform across processes anymore, the properties that they should maintain to support abstractions such as reliable broadcast and consensus are not well-understood. It has been shown that the two properties quorum intersection and availability are necessary. In this paper, we prove that they are not sufficient. We then define the notion of quorum subsumption, and show that the three conditions together are sufficient: we present reliable broadcast and consensus protocols, and prove their correctness for quorum systems that provide the three properties.

Andrew Cullen, Lianna Zhao, Luigi Vigneri et al.

An outstanding problem in the design of distributed ledgers concerns policies that govern the manner in which users interact with the network. Network usability is crucial to the mainstream adoption of distributed ledgers, particularly for enterprise applications in which most users do not wish to operate full node. For DAG-based ledgers such as IOTA, we propose a user-node interaction mechanism that is designed to ensure the risk of a user experiencing a poor quality of service is low. Our mechanism involves users selecting nodes to issue their transactions to the ledger based on quality of service indicators advertised by the nodes. Simulation results are presented to illustrate the efficacy of the proposed policies.

Guoxiang Grayson Tong, Daniele E. Schiavazzi

We propose a data-driven framework to increase the computational efficiency of the explicit finite element method in the structural analysis of soft tissue. An encoder-decoder long short-term memory deep neural network is trained based on the data produced by an explicit, distributed finite element solver. We leverage this network to predict synchronized displacements at shared nodes, minimizing the amount of communication between processors. We perform extensive numerical experiments to quantify the accuracy and stability of the proposed synchronization-avoiding algorithm.

Muhammad Osama, Serban D. Porumbescu, John D. Owens

We identify the graph data structure, frontiers, operators, an iterative loop structure, and convergence conditions as essential components of graph analytics systems based on the native-graph approach. Using these essential components, we propose an abstraction that captures all the significant programming models within graph analytics, such as bulk-synchronous, asynchronous, shared-memory, message-passing, and push vs. pull traversals. Finally, we demonstrate the power of our abstraction with an elegant modern C++ implementation of single-source shortest path and its required components.

Hanwen Zhang, Yanbo Wang, Zhe Chen

Hasan Heydari, Guthemberg Silvestre, Luciana Arantes

Weighted voting is a conventional approach to improving the performance of replicated systems based on commonly-used majority quorum systems in heterogeneous environments. In long-lived systems, a weight reassignment protocol is required to reassign weights over time in order to accommodate performance variations accordingly. The weight reassignment protocol should be consensus-free in asynchronous failure-prone systems because of the impossibility of solving consensus in such systems. This paper presents an efficient consensus-free weight reassignment protocol for atomic storage systems in heterogeneous, dynamic, and asynchronous message-passing systems. An experimental evaluation shows that the proposed protocol improves the performance of atomic read/write storage implemented by majority quorum systems compared with previous solutions.

Dave Dice, Alex Kogan

Creating and destroying threads on modern Linux systems incurs high latency, absent concurrency, and fails to scale as we increase concurrency. To address this concern we introduce a process-local cache of idle threads. Specifically, instead of destroying a thread when it terminates, we cache and then recycle that thread in the context of subsequent thread creation requests. This approach shows significant promise in various applications and benchmarks that create and destroy threads rapidly and illustrates the need for and potential benefits of improved concurrency infrastructure. With caching, the cost of creating a new thread drops by almost an order of magnitude. As our experiments demonstrate, this results in significant performance improvements for multiple applications that aggressively create and destroy numerous threads.

Idit Keidar, Eleftherios Kokoris-Kogias, Oded Naor et al.

We present DAG-Rider, the first asynchronous Byzantine Atomic Broadcast protocol that achieves optimal resilience, optimal amortized communication complexity, and optimal time complexity. DAG-Rider is post-quantum safe and ensures that all messages proposed by correct processes eventually get decided. We construct DAG-Rider in two layers: In the first layer, processes reliably broadcast their proposals and build a structured Directed Acyclic Graph (DAG) of the communication among them. In the second layer, processes locally observe their DAGs and totally order all proposals with no extra communication.

Geunsik Lim, Donghwa Lee, Sang-Bum Suh

Online educational systems running on smart devices have the advantage of allowing users to learn online regardless of the location of the users. In particular, data synchronization enables users to cooperate on contents in real time anywhere by sharing their files via cloud storage. However, users cannot collaborate by simultaneously modifying files that are shared with each other. In this paper, we propose a content collaboration method and a history management technique that are based on distributed system structure and can synchronize data shared in the cloud for multiple users and multiple devices.

Joel Mandebi Mbongue, Danielle Tchuinkou Kwadjo, Christophe Bobda

Virtualization has gained astonishing popularity in recent decades. It is applied in several application domains, including mainframes, personal computers, data centers, and embedded systems. While the benefits of virtualization are no longer to be demonstrated, it often comes at the price of performance degradation compared to native execution. In this work, we conduct a comparative study on the performance outcome of VMWare, KVM, and Docker against compute-intensive, IO-intensive, and system benchmarks. The experiments reveal that containers are the way-to-go for the fast execution of applications. It also shows that VMWare and KVM perform similarly on most of the benchmarks.