GroupingSearch with groupLimit or groupDocsLimit = Integer.MAX_VALUE ('all remaining groups/documents') throws NegativeArraySizeException, OutOfMemoryError or an IllegalArgumentException naming -2147483648, because it does not cap the limits at maxDoc as IndexSearcher.search does and its collectors add offset + limit in int (every release since 4.0.0)
Finding LFV-964Area: grouping / GroupingSearch (term, function, cached two-pass and doc-block grouping) x the first-pass, TopGroups and block collector managersPriority: 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 call GroupingSearch.search(searcher, query, 0, Integer.MAX_VALUE) or setGroupDocsLimit(Integer.MAX_VALUE) to get every group, or every document of each group, and expect the same TopGroups as with a limit of maxDoc, the way IndexSearcher.search(query, Integer.MAX_VALUE) returns every hit. Instead the search throws: with offset 0 a NegativeArraySizeException -2147483648, an OutOfMemoryError 'Requested array size exceeds VM limit' or a queue-size IllegalArgumentException, and with offset 1 an IllegalArgumentException such as 'topNGroups must be >= 1 (got -2147483648)' or 'numHits must be > 0'. GroupingSearch hands the limits on uncapped to collectors that add offset + limit in int and pre-size their queues by the limit; nothing is ever returned wrong.
The test shows that GroupingSearch.search(searcher, query, 0, Integer.MAX_VALUE) ("all groups") throws on a 1-document index, because GroupingSearch does not cap the limit at maxDoc as IndexSearcher.search does.
Expected vs actual
Expected the 1 group that a limit of maxDoc returns; actual: NegativeArraySizeException: -2147483648 (topNGroups + 1 wraps), 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/grouping/build/libs/lucene-grouping-$V.jar
CP=$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.grouping.TestGroupingSearchLimitMaxValueGradle 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).
Formal models and scripts this finding's part of the hunt used: grouping-offset-plus-limit-overflow
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.