Formal models and scripts: japanese-completion-fifo

Tools: Python

These are the working models and scripts this part of the hunt used. Some encode the code as it is (a counterexample is the expected result), others a fixed or correct variant; read the header comment of each file. Paths inside them were replaced by placeholders such as $LUCENE (a Lucene checkout) and $WORK.

Findings

• JapaneseCompletionFilter expands a reading into every combination of romaji spellings with no bound, so 24-32 kana (for example 32 x "ン", or 32 x "し" in QUERY mode) throw OutOfMemoryError inside one incrementToken() call (finding LFV-346; repro · finding page)

Files

• romaji-expansion-unbounded-cartesian-product/model/romaji_growth.py (used for LFV-346)

How to run

• Python: python3 <file>.py; scripts that import z3 need the z3-solver package.

Snapshot of 2026-11-03. AI-assisted; not yet triaged by a human Lucene committer. Feedback: open an issue in lucene-ai-bug-hunt.