vLLM fork enables post-thinking sampling to fix Qwen 3.8 quality
TokenRingAI · reddit · 2026-08-19
A developer published a vLLM branch that allows separate sampler settings for the post-thinking block, significantly improving the output and reliability of Qwen 3.8 27B.
Problem:
Qwen 3.8 27B requires a high temperature (0.9-1.0) during thinking to prevent loops, but the same high temperature makes the final answer sloppy.
Solution:
The fork introduces a postthinking config, allowing different sampling parameters (e.g., temperature 0.2) for content after the thinking block.
Usage:
- Set globally via --override-generation-config at launch.
- Or set per request via extrabody.
Initial results show significantly fewer errors in the generated output while maintaining identical thinking quality.
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