UnifiedHighlighter with maxPassages = Integer.MAX_VALUE throws a message-less IllegalArgumentException for every document that has a match (FieldHighlighter sizes its passage queue with Math.min(64, maxPassages + 1), which wraps)
Finding LFV-438Area: highlighter / UnifiedHighlighter passage selection (FieldHighlighter.highlightOffsetsEnums passage-queue sizing; maxPassages is never range-checked by UnifiedHighlighter.highlightFieldsAsObjects)Priority: lowImpact: wrong errorNovelty: new
AI-assisted finding, confirmed by automated checks, not yet triaged by a human Lucene committer. This site files nothing upstream.
What it shows
You ask the UnifiedHighlighter for at most Integer.MAX_VALUE passages, meaning 'no limit', and expect the same snippet that 1000 or Integer.MAX_VALUE - 1 gives (or, if the value is not allowed, an IllegalArgumentException that says so). Instead, for every document that has a match, FieldHighlighter.highlightOffsetsEnums sizes its passage queue with Math.min(64, maxPassages + 1); the + 1 wraps to Integer.MIN_VALUE, Math.min returns it, and the java.util.PriorityQueue constructor throws an IllegalArgumentException with no message. With per-field counts such as {1, MAX_VALUE} the field that asked for one passage loses its snippet too, because the whole call throws.
The test shows that UnifiedHighlighter with maxPassages = Integer.MAX_VALUE (no limit) fails for a matching text, because FieldHighlighter sizes its passage queue with Math.min(64, maxPassages + 1), which wraps to Integer.MIN_VALUE.
Expected vs actual
Expected the snippet that maxPassages = 1000 gives (a <b>test</b>); actual: a message-less IllegalArgumentException from java.util.PriorityQueue.<init> at FieldHighlighter.java:143, with -ea and -da.
Files
Run it
- Tested on Lucene main e1faeba08bde (2026-11-02): still reproduces.
- Tested on Lucene main 645d4fe14a20 (2026-10-28): reproduced.
- Recorded outcome of run 1 on Lucene main 645d4fe14a20: 1 test(s) run, 1 failed.
- How to read the outcome: a failing test is the finding reproducing (the failure message states expected against actual).
- Seeds: a rerun with the same seed replays the same random choices. Assertions off (-da -dsa -Dtests.asserts=false) is the production-like setting.
# Lucene checkout at the tested commit, built with: ./gradlew --no-daemon assemble (JDK 25)
LUCENE=/path/to/lucene; V=12.0.0-SNAPSHOT
CP=$LUCENE/lucene/core/build/libs/lucene-core-$V.jar
CP=$CP:$LUCENE/lucene/codecs/build/libs/lucene-codecs-$V.jar
CP=$CP:$LUCENE/lucene/test-framework/build/libs/lucene-test-framework-$V.jar
CP=$CP:$LUCENE/lucene/highlighter/build/libs/lucene-highlighter-$V.jar
CP=$CP:$LUCENE/lucene/memory/build/libs/lucene-memory-$V.jar
CP=$CP:$LUCENE/lucene/queries/build/libs/lucene-queries-$V.jar
CP=$CP:randomizedtesting-runner-2.9.2.jar:junit-4.13.2.jar:hamcrest-3.0.jar # test-framework dependencies (Maven Central)
CP=$CP:junit-platform-console-standalone-6.1.3.jar # JUnit Platform console launcher (Maven Central)
javac -d classes -cp "$CP" $(find src -name '*.java')
# run 1: assertions on, seed DEADBEEF
java -ea -esa --add-modules jdk.incubator.vector --enable-native-access=ALL-UNNAMED -Dtests.seed=DEADBEEF \
-cp "classes:$CP" org.junit.platform.console.ConsoleLauncher \
execute --select-class org.apache.lucene.search.uhighlight.TestUnifiedHighlighterMaxValueMaxPassagesGradle alternative: copy the test into the matching module's src/test/ tree of the checkout and run ./gradlew -p lucene/<module> test --tests <class> -Ptests.seed=<seed> (add -Ptests.asserts=false for a run without assertions).
Feedback
Open an issue in lucene-ai-bug-hunt. Please do not open issues or pull requests in apache/lucene about this finding unless a Lucene committer agrees it should be filed.
Snapshot of 2026-11-04. AI-assisted; not yet triaged by a human Lucene committer. Feedback: open an issue in lucene-ai-bug-hunt.