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On the Origin and Evolution of Training-Inference Mismatch in LLM Reinforcement Learning

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 tr

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Nov 2, 2026First seen
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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
Upvotes
6
Authors
3
Published
Oct 29, 2026

Summary and abstract excerpt via Hugging Face Papers ↗ · arXiv.

Trending history

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.

Rank history

Position on Hugging Face · Daily papers at every check (lower is better).

#1#11#20#30 15:2819:2823:2803:2807:28 Nov 2, 15:28 UTC · #29Nov 2, 17:28 UTC · #25Nov 2, 19:28 UTC · #23Nov 2, 21:28 UTC · #23Nov 2, 23:28 UTC · #23Nov 3, 01:28 UTC · #23Nov 3, 03:28 UTC · #20Nov 3, 05:28 UTC · #25Nov 3, 07:28 UTC · #24

Last 14 days

Best rank per day (UTC).

Oct 26today

Metric history

Platform metric as reported by Hugging Face.

0369 15:2819:2823:2803:2807:28 Nov 2, 15:28 UTC · 6Nov 2, 17:28 UTC · 7Nov 2, 19:28 UTC · 8Nov 2, 21:28 UTC · 8Nov 2, 23:28 UTC · 9Nov 3, 01:28 UTC · 9Nov 3, 03:28 UTC · 9Nov 3, 05:28 UTC · 9Nov 3, 07:28 UTC · 9

Questions

Is On the Origin and Evolution of Training-Inference Mismatch in LLM Reinforcement Learning trending on HF Daily Papers right now?

Not at the moment. It was last on the list on Nov 3, 07:28 UTC, after 2 days of trending.

What is the highest rank On the Origin and Evolution of Training-Inference Mismatch in LLM Reinforcement Learning reached?

#20 on Hugging Face · Daily papers, on Nov 3, 03:28 UTC. Trendoday checks this list every 120 minutes.

How long has On the Origin and Evolution of Training-Inference Mismatch in LLM Reinforcement Learning been trending?

It was first seen on Nov 2, 2026 and has been on the list on 2 days (9 checks) since.