Suppressing LLM Repetition Hallucinations with a Custom Logits Processor in Qwen
Fine-tuning Qwen for structured JSON output can trigger repetition hallucinations where the model loops the same phrase indefinitely. Standard parameters like no_repeat_ngram_size suppress this globally, causing unintended side effects across the entire output. This article implements a custom Transformers LogitsProcessor that applies repetition control exclusively inside the target JSON field, eliminating loops without breaking the surrounding structure.