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一种基于动态拓扑的流计算性能优化方法及其在Storm中的实现 被引量:7
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作者 陆佳炜 吴涵 +3 位作者 陈烘 张元鸣 梁倩卉 肖刚 《电子学报》 EI CAS CSCD 北大核心 2020年第5期878-890,共13页
响应性和稳定性一直是流式计算中两个至关重要的问题,而流计算系统在过载时常常表现出数据计算延迟增加和拓扑不稳定的现象,无法适应数据负载的动态变化.针对这一问题本文研究提出了一种基于动态拓扑的流计算性能优化方法,主要包括:(1)... 响应性和稳定性一直是流式计算中两个至关重要的问题,而流计算系统在过载时常常表现出数据计算延迟增加和拓扑不稳定的现象,无法适应数据负载的动态变化.针对这一问题本文研究提出了一种基于动态拓扑的流计算性能优化方法,主要包括:(1)动态逐级反压:拓扑中的任务可以根据当前自身负载情况,动态调整上游向其发送数据的速率.(2)无状态拓扑数据重放:拓扑不维持数据的计算状态,尽可能地实现数据容错.(3)自适应拓扑替换:在拓扑不暂停的情况下对任务并发度进行自发调整.(4)延迟持久化队列:拓扑中对磁盘的IO读写被延迟到数据处理之外,减缓IO高频阻塞对流计算系统的影响.本文在Apache Storm中实现了以上四种方案,性能测试结果表明优化后的流计算系统与Storm默认实现相比,不仅增强了大数据动态匹配能力,而且在最优情况下改善了17%的吞吐量,并提升了约20%的数据处理速度. 展开更多
关键词 数据流拓扑 流计算 数据 流计算系统 性能优化
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Image feature optimization based on nonlinear dimensionality reduction 被引量:3
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作者 Rong ZHU Min YAO 《Journal of Zhejiang University-Science A(Applied Physics & Engineering)》 SCIE EI CAS CSCD 2009年第12期1720-1737,共18页
Image feature optimization is an important means to deal with high-dimensional image data in image semantic understanding and its applications. We formulate image feature optimization as the establishment of a mapping... Image feature optimization is an important means to deal with high-dimensional image data in image semantic understanding and its applications. We formulate image feature optimization as the establishment of a mapping between highand low-dimensional space via a five-tuple model. Nonlinear dimensionality reduction based on manifold learning provides a feasible way for solving such a problem. We propose a novel globular neighborhood based locally linear embedding (GNLLE) algorithm using neighborhood update and an incremental neighbor search scheme, which not only can handle sparse datasets but also has strong anti-noise capability and good topological stability. Given that the distance measure adopted in nonlinear dimensionality reduction is usually based on pairwise similarity calculation, we also present a globular neighborhood and path clustering based locally linear embedding (GNPCLLE) algorithm based on path-based clustering. Due to its full consideration of correlations between image data, GNPCLLE can eliminate the distortion of the overall topological structure within the dataset on the manifold. Experimental results on two image sets show the effectiveness and efficiency of the proposed algorithms. 展开更多
关键词 Image feature optimization Nonlinear dimensionality reduction Manifold learning Locally linear embedding (LLE)
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