Optimizing Recommendation Systems with JDK’s Vector API

431 · Netflix, Inc. · March 3, 2026, 2:11 a.m.
Summary
This blog post discusses the optimization of Netflix's Ranker service by improving the efficiency of its video serendipity scoring feature through the use of JDK's Vector API. The author outlines the challenges faced in CPU utilization, the transition to matrix operations for scoring, and the final implementation of a SIMD-style approach using the JDK Vector API that resulted in significant performance gains. Key lessons include the importance of data layout and computational shapes in achieving optimizations.