scholarly journals Massively Parallel Computation via Remote Memory Access

2021 ◽  
Vol 8 (3) ◽  
pp. 1-25
Author(s):  
Soheil Behnezhad ◽  
Laxman Dhulipala ◽  
Hossein Esfandiari ◽  
Jakub Łącki ◽  
Vahab Mirrokni ◽  
...  
Keyword(s):  
Parallel Computation ◽  
Graph Algorithms ◽  
Minimum Spanning Tree ◽  
Empirical Studies ◽  
Hash Table ◽  
Massively Parallel ◽  
Remote Memory ◽  
Distributed Hash Table ◽  
Maximal Independent Set ◽  
Data Store

We introduce the Adaptive Massively Parallel Computation (AMPC) model, which is an extension of the Massively Parallel Computation (MPC) model. At a high level, the AMPC model strengthens the MPC model by storing all messages sent within a round in a distributed data store. In the following round, all machines are provided with random read access to the data store, subject to the same constraints on the total amount of communication as in the MPC model. Our model is inspired by the previous empirical studies of distributed graph algorithms [8, 30] using MapReduce and a distributed hash table service [17]. This extension allows us to give new graph algorithms with much lower round complexities compared to the best-known solutions in the MPC model. In particular, in the AMPC model we show how to solve maximal independent set in O (1) rounds and connectivity/minimum spanning tree in O (log log m / n n rounds both using O ( n δ ) space per machine for constant δ < 1. In the same memory regime for MPC, the best-known algorithms for these problems require poly log n rounds. Our results imply that the 2-C YCLE conjecture, which is widely believed to hold in the MPC model, does not hold in the AMPC model.

scholarly journals Massively Parallel Computation via Remote Memory Access

2019 ◽  
Author(s):  
Soheil Behnezhad ◽  
Laxman Dhulipala ◽  
Hossein Esfandiari ◽  
Jakub Łącki ◽  
Vahab Mirrokni ◽  
...  
Keyword(s):  
Parallel Computation ◽  
Memory Access ◽  
Massively Parallel ◽  
Remote Memory ◽  
Remote Memory Access

scholarly journals Graph Sparsification for Derandomizing Massively Parallel Computation with Low Space

2021 ◽  
Vol 17 (2) ◽  
pp. 1-27
Author(s):  
Artur Czumaj ◽  
Peter Davies ◽  
Merav Parter
Keyword(s):  
Parallel Computation ◽  
Independent Set ◽  
Massively Parallel ◽  
Easy Access ◽  
Maximal Independent Set ◽  
Input Graph ◽  
Single Node ◽  
Maximal Matching ◽  
Graph Problems ◽  
Graph Sparsification

The Massively Parallel Computation (MPC) model is an emerging model that distills core aspects of distributed and parallel computation, developed as a tool to solve combinatorial (typically graph) problems in systems of many machines with limited space. Recent work has focused on the regime in which machines have sublinear (in n , the number of nodes in the input graph) space, with randomized algorithms presented for the fundamental problems of Maximal Matching and Maximal Independent Set. However, there have been no prior corresponding deterministic algorithms. A major challenge underlying the sublinear space setting is that the local space of each machine might be too small to store all edges incident to a single node. This poses a considerable obstacle compared to classical models in which each node is assumed to know and have easy access to its incident edges. To overcome this barrier, we introduce a new graph sparsification technique that deterministically computes a low-degree subgraph, with the additional property that solving the problem on this subgraph provides significant progress towards solving the problem for the original input graph. Using this framework to derandomize the well-known algorithm of Luby [SICOMP’86], we obtain O (log Δ + log log  n )-round deterministic MPC algorithms for solving the problems of Maximal Matching and Maximal Independent Set with O ( n ɛ ) space on each machine for any constant ɛ > 0. These algorithms also run in O (log Δ) rounds in the closely related model of CONGESTED CLIQUE, improving upon the state-of-the-art bound of O (log  2 Δ) rounds by Censor-Hillel et al. [DISC’17].

scholarly journals Agent-Based Coordinated Control of Power Electronic Converters in a Microgrid

Electronics ◽  
2021 ◽  
Vol 10 (9) ◽  
pp. 1031
Author(s):  
Maryam Nasri ◽  
Herbert L. Ginn ◽  
Mehrdad Moallem
Keyword(s):  
Hash Table ◽  
Power Sharing ◽  
Distributed Hash Table ◽  
Power Electronic ◽  
Power Electronic Converters ◽  
Agent Based ◽  
Development Framework ◽  
Study Results ◽  
Set Up ◽  
Microgrid Control

This paper presents the implementation of an agent-based architecture suitable for the coordination of power electronic converters in stand-alone microgrids. To this end, a publish-subscribe agent architecture was utilized as a distributed microgrid control platform. Over a distributed hash table (DHT) searching overlay, the publish-subscribe architecture was identified based on a numerical analysis as a scalable agent-based technology for the distributed real-time coordination of power converters in microgrids. The developed framework was set up to deploy power-sharing distributed optimization algorithms while keeping a deterministic time period of a few tens of milliseconds for a system with tens of converters and when multiple events might happen concurrently. Several agents participate in supervisory control to regulate optimum power-sharing for the converters. To test the design, a notional shipboard system, including several converters, was used as a case study. Results of implementing the agent-based publish-subscribe control system using the Java Agent Development Framework (JADE) are presented.

Improved Blockchain Commodity Traceability System Using Distributed Hash Table

2020 ◽  
Author(s):  
Wu Junhui ◽  
Wu Tuolei ◽  
Wu Yusheng ◽  
Chen Jie ◽  
Lin Kaiyan ◽  
...  
Keyword(s):  
Hash Table ◽  
Distributed Hash Table ◽  
Traceability System

scholarly journals The Management Strategy of Metadata in Large-scale Network Storage System

2018 ◽  
Vol 228 ◽  
pp. 01011
Author(s):  
Haifeng Zhong ◽  
Jianying Xiong
Keyword(s):  
Large Scale ◽  
Storage System ◽  
Hash Table ◽  
Distributed Hash Table ◽  
Distributed Data ◽  
Mass Storage ◽  
Large Scale Network ◽  
Network Storage System ◽  
Mass Storage System ◽  
Scale Network

The wan Internet storage system based on Distributed Hash Table uses fully distributed data and metadata management, and constructs an extensible and efficient mass storage system for the application based on Internet. However, such systems work in highly dynamic environments, and the frequent entry and exit of nodes will lead to huge communication costs. Therefore, this paper proposes a new hierarchical metadata routing management mechanism based on DHT, which makes full use of the node stabilization point to reduce the maintenance overhead of the overlay. Analysis shows that the algorithm can effectively improve efficiency and enhance stability.

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