用单一模型替代多阶段推荐系统,实现生成与排序一体化。
Gryphon-v2: One Model in Place of a Cascade - Generate-and-Rank Recommender with Rollout Distillation

- 统一生成与排序架构,仅需一次用户历史编码
- 通过滚动蒸馏将高容量排序器知识迁移到模型中
- 在网易音乐上线实验,活跃用户提升1.41%
工业级推荐系统通常采用多阶段级联结构,包含独立的候选生成、预排序和最终排序模块。尽管有效,但这类结构需重复处理用户历史、维护复杂特征管道,并部署多个服务阶段。基于语义ID的生成式检索为构建端到端系统提供了可能,但单纯下一物品预测无法捕捉生产环境中精细的排序目标偏好。本文提出Gryphon-v2,一种统一的生成-排序架构,可实现端到端推荐。模型仅编码用户历史一次,使用自回归解码器生成语义ID候选,将其映射回商品目录,并通过复用共享编码器状态的项目级排序模块进行打分。为在不增加服务路径开销的前提下迁移生产环境中的精细排序偏好,我们通过蒸馏将一个高容量、仅训练时使用的教师排序器知识注入排序模块。Gryphon-v2采用滚动蒸馏训练:仅以教师得分作为排序监督信号,并从两种互补的候选分布中收集得分——当前解码器生成的候选反映实际推理过程,而日志曝光数据覆盖用户真实看到的项目。在网易音乐大规模推荐场景的在线A/B实验中,单个Gryphon-v2模型成功替代了超过15个候选生成器、预排序和最终排序组成的生产级联,部署后活跃用户数提升1.41%,同时保持与原系统相当的服务延迟。结果表明,基于教师排序器蒸馏的生成检索器与排序模块组合,是取代生产级联的可行端到端方案。
原文摘要 · Abstract (English)
Industrial recommender systems are commonly deployed as multi-stage cascades with separate candidate generators, pre-rankers, and final rankers. Although effective, these cascades require repeated user-history processing, complex feature pipelines, and multiple serving stages. Semantic-ID-based generative retrieval offers a path toward simpler end-to-end systems, but next-item prediction alone does not capture the fine-grained preferences encoded by production ranking objectives. We present Gryphon-v2, a unified generate-and-rank architecture for end-to-end recommendation. The model encodes a user history once, generates Semantic-ID candidates with an autoregressive decoder, resolves them to catalogue items, and ranks them with an item-level Ranking Module that reuses the shared encoder states. To transfer fine-grained production ranking preferences without adding an expensive second model to the serving path, we distill a high-capacity, training-only Teacher Ranker into the Ranking Module. Gryphon-v2 is trained with Rollout Distillation: teacher scores are the only ranking supervision, and they are collected over two complementary candidate distributions. Rollouts from the current decoder expose the Ranking Module to candidates produced by the same generation mechanism used at serving time, while logged impressions cover items users were actually shown. In an online A/B experiment on a large-scale recommendation surface at Yandex Music, a single Gryphon-v2 model replaces a production cascade comprising more than 15 candidate generators, pre-ranking, and final ranking. The deployment increases the number of active users by 1.41% at serving latency comparable to the production cascade. These results support the practical viability of a generative retriever with a Ranking Module distilled from the Teacher Ranker as an end-to-end alternative to a production cascade.
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