Semi-sparse algorithm based on multi-layer optimization for recommender system

  • Authors:
  • Hu Guan;Huakang Li;Cheng-Zhong Xu;Minyi Guo

  • Affiliations:
  • Department of Computer Science & Engineering, Shanghai Jiao Tong University, Shanghai, P.R. China;Department of Computer Science & Engineering, Shanghai Jiao Tong University, Shanghai, P.R. China;Department of Electrical and Computer Engineering, Wayne State University, Detroit, USA;Department of Computer Science & Engineering, Shanghai Jiao Tong University, Shanghai, P.R. China

  • Venue:
  • The Journal of Supercomputing
  • Year:
  • 2013

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Abstract

Similarity among vectors is basic knowledge required to carry out recommendation and classification in recommender systems, which support personalized recommendation during online interactions. In this paper, we propose a Semi-sparse Algorithm based on Multi-layer Optimization to speed up the Pearson Correlation Coefficient, which is conventionally used in obtaining similarity among sparse vectors. In accelerating the batch of similarity-comparisons within one thread, the semi-sparse algorithm spares out over-reduplicated accesses and judgements on the selected sparse vector by making this vector dense locally. Moreover, a reduce-vector is proposed to restrict using locks on critical resources in the thread-pool, which is wrapped with Pthreads on a multi-core node to improve parallelism. Furthermore, among processes in our framework, a shared zip file is read to cut down messages within the Message Passing Interface package. Evaluation shows that the optimized multi-layer framework achieves a brilliant speedup on three benchmarks, Netflix, MovieLens and MovieLen1600.