About this paper
On-policy reinforcement learning for large language models suffers from training-inference mismatch due to numerical discrepancies and policy lag, and a derived discrepancy-lag correction stabilizes training by centering errors, clipping importance ratios, and resynchronizing sampling.
On-policy reinforcement learning for large language models assumes that training responses are sampled from the current policy. In practice, an inference engine samples the responses and a separate trainer computes the gradients, and the training-inference mismatch between the two makes the training data off-policy. The mismatch has two sources, the numerics of the engine and the stale weights of asynchronous sampling, and a correction that stabilizes training under one source can fail under the other. We ask which property of a mismatch source decides the correction it needs. Evaluating the trainer at the sampler's weights splits each sampled-token error exactly into a numerical…
on-policy reinforcement learninglarge language modelstraining-inference mismatchnumerical discrepancypolicy lagimportance weightingdiscrepancy-lag correctionKL divergence
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- Published
- Oct 29, 2026
Summary and abstract excerpt via Hugging Face Papers ↗ · arXiv.
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On the Origin and Evolution of Training-Inference Mismatch in LLM Reinforcement Learning was first seen on Hugging Face · Daily papers on Nov 2, 2026. Since then it has appeared in 9 checks on 2 different days. Its best position was #20 of 30, reached on Nov 3, 03:28 UTC. It dropped off the list after Nov 3, 07:28 UTC.