Alibaba Introduces Group Sequence Policy Optimization (GSPO): An Efficient Reinforcement Learning Algorithm that Powers the Qwen3 Models
Reinforcement learning (RL) plays a crucial role in scaling language models, enabling them to solve complex tasks such as competition-level mathematics and programming through deeper reasoning. However, achieving stable and reliable training dynamics is a challenge when scaling RL with larger computational resources. Current state-of-the-art algorithms, such as GRPO, struggle with serious stability issues during the training of gigantic language models, often resulting in catastrophic failures. These instabilities arise from incorrect use of importance sampling weight applications, which introduce high-variance noise. This noise accumulates with longer responses and is worsened by clipping mechanisms. This causes model collapse and hinders progress. Existing methods like PPO and GRPO rely on mechanisms like clipping to address off-policy learning challenges where responses are taken from outdated policies. However, these approaches face limitations due to their ill-posed objectives, p...