DoubleValuesSourceRescorer and LateInteractionRescorer throw NoSuchElementException instead of returning no hits when the searcher's reader has no segments: rescore() takes leaves().getFirst() before it looks at the hits

Finding LFV-329Area: search / rescoringPriority: lowImpact: crashNovelty: new

Finding page for LFV-329

AI-assisted finding, confirmed by automated checks, not yet triaged by a human Lucene committer. This site files nothing upstream.

What it shows

You search an index that has no segments yet (for example a freshly created or emptied index, or an empty shard), get the expected 0 hits, and pass them to a DoubleValuesSourceRescorer or LateInteractionRescorer. You expect 0 rescored hits, which is what QueryRescorer and SortRescorer return for the same input. Instead rescore() throws java.util.NoSuchElementException, because it takes the reader's first segment with leaves().getFirst() before it looks at the hits, and there is no first segment.

The test shows that DoubleValuesSourceRescorer.rescore on a searcher whose reader has no segments (here an empty MultiReader, same as a fresh empty index) throws instead of returning the 0 first-pass hits.

Expected vs actual

Expected: 0 rescored hits, as QueryRescorer returns; actual (-ea and -da): java.util.NoSuchElementException from leaves().getFirst() at DoubleValuesSourceRescorer.java:53 (reported as an AssertionError with that cause).

Files

• src/org/apache/lucene/search/TestDoubleValuesSourceRescorerNoSegments.java (JUnit test)

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=$CP:randomizedtesting-runner-2.9.2.jar:junit-4.13.2.jar:hamcrest-3.0.jar   # test-framework dependencies (Maven Central)
CP=$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.TestDoubleValuesSourceRescorerNoSegments

Gradle 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.