Preventing Entropy Collapse in Long RL Runs

Source: https://x.com (tweet) Author: unknown (RL researcher, community Q&A) Date: 2025-2026

Summary

Community Q&A on tricks to prevent entropy collapse during long LLM RL runs. Key trick: optimize Best-of-N (pass@N) rewards to maintain diversity. Thread soliciting community knowledge on other techniques.

Key Claims

  • Entropy collapse is a real failure mode in long RL runs
  • Primary trick: optimizing Best-of-N rewards (reward diversity, not just quality)
  • Community knowledge is fragmented — practitioners share different techniques
  • Open question: what other diversity-preservation tricks work at scale

Connection to Other Sources

Connects to RL Collapse and FP16 vs BF16 for RL.

Concepts