Why Local Models Get Stuck in JSON Repetition Loops

mattjcoles · reddit · 2026-07-16

The author initially thought Qwen3-VL-30B was simply too slow for document extraction, but running it on a 5090 revealed a deeper issue: the model falling into a loop, repeatedly outputting the same valid JSON block.

Testing it on a 37-page document and comparing its performance with Gemma, the author highlights why models face this "repetition trap" under syntax constraints. This is a critical issue for local models performing structured extraction, as the output may appear perfectly formatted while the actual task has already failed.

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