On-Device Next-Item Recommendation with Self-Supervised Knowledge Distillation

TL;DR

This paper introduces an ultra-compact on-device recommendation model using self-supervised knowledge distillation, achieving significant size reduction with minimal accuracy loss and improved long-tail item recommendation.

Contribution

It proposes a novel ultra-compact model for on-device recommendation that relaxes tensor decomposition constraints and employs self-supervised knowledge distillation to retain performance.

Findings

30x model size reduction with almost no accuracy loss

Compressed model outperforms uncompressed in most cases

Effective long-tail item recommendation enhancement

Abstract

Modern recommender systems operate in a fully server-based fashion. To cater to millions of users, the frequent model maintaining and the high-speed processing for concurrent user requests are required, which comes at the cost of a huge carbon footprint. Meanwhile, users need to upload their behavior data even including the immediate environmental context to the server, raising the public concern about privacy. On-device recommender systems circumvent these two issues with cost-conscious settings and local inference. However, due to the limited memory and computing resources, on-device recommender systems are confronted with two fundamental challenges: (1) how to reduce the size of regular models to fit edge devices? (2) how to retain the original capacity? Previous research mostly adopts tensor decomposition techniques to compress the regular recommendation model with limited compression ratio so as to avoid drastic performance degradation. In this paper, we explore ultra-compact models for next-item recommendation, by loosing the constraint of dimensionality consistency in tensor decomposition. Meanwhile, to compensate for the capacity loss caused by compression, we develop a self-supervised knowledge distillation framework which enables the compressed model (student) to distill the essential information lying in the raw data, and improves the long-tail item recommendation through an embedding-recombination strategy with the original model (teacher). The extensive experiments on two benchmarks demonstrate that, with 30x model size reduction, the compressed model almost comes with no accuracy loss, and even outperforms its uncompressed counterpart in most cases.