What problem does it solve?
This Skill helps you train large language models using reinforcement learning methods (RLHF/GRPO/PPO and related variants) efficiently across distributed infrastructure, without stitching together complex rollout, reward, and training components manually.
Core Features & Use Cases
- HybridFlow RL training orchestration: coordinates rollout → reward computation → policy/value updates in a production-ready training loop.
- Backend-flexible scaling: supports major training and rollout backends such as FSDP/FSDP2/Megatron-LM for training and vLLM/SGLang/Transformers for rollout.
- Algorithm coverage for post-training: implements GRPO, PPO (GAE), and multiple reward/baseline strategies suitable for sparse or dense reward settings.
- Use case: fine-tune a math reasoning model on GSM8K-style tasks by sampling multiple responses per prompt and optimizing with GRPO using a custom reward that checks extracted boxed answers.
Quick Start
Run a GRPO math training job with verl by executing a Python invocation that sets adv_estimator=grpo, points to your parquet dataset, selects a HuggingFace base model, sets rollout samples per prompt, and configures the GPU count.