ReSpec: Towards Optimizing Speculative Decoding in Reinforcement Learning Systems

Fuente: arXiv
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Main Authors: Chen, Qiaoling, Liu, Zijun, Sun, Peng, Li, Shenggui, Wang, Guoteng, Liu, Ziming, Wen, Yonggang, Feng, Siyuan, Zhang, Tianwei
Format: Preprint
Published: 2025
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author Chen, Qiaoling
Liu, Zijun
Sun, Peng
Li, Shenggui
Wang, Guoteng
Liu, Ziming
Wen, Yonggang
Feng, Siyuan
Zhang, Tianwei
author_facet Chen, Qiaoling
Liu, Zijun
Sun, Peng
Li, Shenggui
Wang, Guoteng
Liu, Ziming
Wen, Yonggang
Feng, Siyuan
Zhang, Tianwei
contents Adapting large language models (LLMs) via reinforcement learning (RL) is often bottlenecked by the generation stage, which can consume over 75\% of the training time. Speculative decoding (SD) accelerates autoregressive generation in serving systems, but its behavior under RL training remains largely unexplored. We identify three critical gaps that hinder the naive integration of SD into RL systems: diminishing speedups at large batch sizes, drafter staleness under continual actor updates, and drafter-induced policy degradation. To address these gaps, we present ReSpec, a system that adapts SD to RL through three complementary mechanisms: dynamically tuning SD configurations, evolving the drafter via knowledge distillation, and weighting updates by rollout rewards. On Qwen models (3B--14B), ReSpec achieves up to 4.5x speedup while preserving reward convergence and training stability, providing a practical solution for efficient RL-based LLM adaptation.
format Preprint
id arxiv_https___arxiv_org_abs_2510_26475
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle ReSpec: Towards Optimizing Speculative Decoding in Reinforcement Learning Systems
Chen, Qiaoling
Liu, Zijun
Sun, Peng
Li, Shenggui
Wang, Guoteng
Liu, Ziming
Wen, Yonggang
Feng, Siyuan
Zhang, Tianwei
Machine Learning
Distributed, Parallel, and Cluster Computing
Adapting large language models (LLMs) via reinforcement learning (RL) is often bottlenecked by the generation stage, which can consume over 75\% of the training time. Speculative decoding (SD) accelerates autoregressive generation in serving systems, but its behavior under RL training remains largely unexplored. We identify three critical gaps that hinder the naive integration of SD into RL systems: diminishing speedups at large batch sizes, drafter staleness under continual actor updates, and drafter-induced policy degradation. To address these gaps, we present ReSpec, a system that adapts SD to RL through three complementary mechanisms: dynamically tuning SD configurations, evolving the drafter via knowledge distillation, and weighting updates by rollout rewards. On Qwen models (3B--14B), ReSpec achieves up to 4.5x speedup while preserving reward convergence and training stability, providing a practical solution for efficient RL-based LLM adaptation.
title ReSpec: Towards Optimizing Speculative Decoding in Reinforcement Learning Systems
topic Machine Learning
Distributed, Parallel, and Cluster Computing
url https://arxiv.org/abs/2510.26475