TeeSinkTokenFilter: a sink created with newSinkTokenStream() before a filter that adds an attribute is put on the tee (the order of the class javadoc example), for example any stemmer adding KeywordAttribute, throws IllegalArgumentException from restoreState on its first token, so IndexWriter.addDocument rejects the document

Finding LFV-650Area: analysis / TeeSinkTokenFilter (sinks: newSinkTokenStream() attribute snapshot, SinkTokenStream replay through AttributeSource.restoreState)Priority: lowImpact: crashNovelty: new

Finding page for LFV-650

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

What it shows

You create a sink with tee.newSinkTokenStream() and then wrap the tee in a further filter, as the class javadoc example does (sinks first, then final1 = new LowerCaseFilter(source1)), and expect the sink to replay every token the tee consumed, as newSinkTokenStream() promises. If that later filter adds an attribute the tee did not have yet, for example PorterStemFilter adding KeywordAttribute for a stemmed field next to an unstemmed sink field, the sink lacks it, because its attributes are a cloneAttributes() snapshot taken when it was created, and its restoreState throws IllegalArgumentException ('State contains AttributeImpl of type ...KeywordAttributeImpl that is not in in this AttributeSource') on the first token, so addDocument rejects the document. With LowerCaseFilter, the javadoc's own filter, nothing is added and the example works; creating the sink after the stemmer also works.

The test shows that a sink created with tee.newSinkTokenStream() before a PorterStemFilter is put on the tee (the class javadoc's order) cannot replay the token "foxes".

Expected vs actual

Expected the sink to return "foxes"; actual: restoreState throws IllegalArgumentException: State contains AttributeImpl of type ...KeywordAttributeImpl that is not in in this AttributeSource, with -ea and -da.

Files

• src/org/apache/lucene/analysis/sinks/TestTeeSinkAttributeAddedAfterSink.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=$CP:$LUCENE/lucene/analysis/common/build/libs/lucene-analysis-common-$V.jar
CP=$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.analysis.sinks.TestTeeSinkAttributeAddedAfterSink

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.