| Emerging recommender systems often adopt collaborative filtering techniques to improve the recommending accuracy.Existing collaborative filtering techniques are implemented with either Alternating Least Square(ALS)algorithm or Gradient Descent(GD)algorithm.However,both of the two algorithms are not scalable because ALS suffers from high computation complexity and GD suffers from severe synchronization problem and tremendous data movement.To solve the above problems,we proposed a Dataflow-based Collaborative Filtering(DCF)algorithm.More specifically,DCF exploits fine-grain asynchronous feature of dataflow model to minimize synchronization overhead;leverages mini-batch technique to reduce computation and communication complexities;uses dummy edge and multicasting techniques to avoid finegrain overhead of dependency checking and reduce data movement.By utilizing all the above techniques,DCF is able to significantly improve the performance of collaborative filtering.Our experiment on a cluster with one master node and ten slave nodes show that DCF achieves 23 x speedup over ALS on Spark and 18 x speedup over GD on Graphlab in public datasets.er ALS based collaborative filtering algorithm on Apache Spark in Netflix dataset. |
