AGGC: Adaptive Group Gradient Clipping for Stabilizing Large Language Model Training

摘要

To stabilize the training of Large Language Models (LLMs), gradient clipping is a nearly ubiquitous heuristic used to alleviate exploding gradients. However, traditional global norm clipping erroneously presupposes gradient homogeneity across different functional modules, leading to an adverse "spill-over" effect where volatile parameters force unnecessary scaling on stable ones. To overcome this, we propose Adaptive Group-wise Gradient Clipping (AGGC). AGGC partitions parameters into groups based on functional types and regulates each according to its historical behavior using an Exponential Moving Average (EMA). Specifically, it constructs an adaptive interval to simultaneously mitigate gradient explosion and vanishing, while employing a time-dependent scheduling mechanism to balance exploration and convergence. Experiments on LLaMA 2-7B, Mistral-7B, and Gemma-7B models demonstrate that AGGC-enhanced LoRA consistently outperforms standard LoRA and frequently exceeds Full Fine-Tuning performance. Specifically, on the GSM8K benchmark, Mistral-7B fine-tuned with AGGC-enhanced LoRA achieves 72.93% accuracy, surpassing the 69.5% of vanilla LoRA. AGGC also contributes to the stability of Reinforcement Learning with Verifiable Rewards (RLVR), leading to improved logical deduction in Qwen 2.5 and Llama 3.2 models. Experimental results demonstrate that AGGC effectively addresses the limitations of traditional gradient clipping methods, particularly in overcoming gradient heterogeneity, by utilizing a modular, adaptive clipping strategy to stabilize the training process. Due to its lightweight design, AGGC can be seamlessly integrated into existing post-training pipelines with negligible overhead.