[LUCENE-7002] MultiCollector throws NPE when there is CollectTerminatedException is thrown by a subcollector

• Type: Bug
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Affects Version/s: 5.4
• Fix Version/s: 5.4.2, 5.5
• Component/s: core/search
• Lucene Fields: New
• Assignee: Adrien Grand
• Reporter: John Wang
• Created: 29/Jan/16 16:46
• Updated: 28/Aug/22 14:49
• Resolved: 10/Feb/16 16:28

Description

I am seeing this in our log:

Caused by: java.lang.NullPointerException
        at org.apache.lucene.search.MultiCollector$MultiLeafCollector.setScorer(MultiCollector.java:156)
        at org.apache.lucene.search.BooleanScorer$1$1.setScorer(BooleanScorer.java:50)
        at org.apache.lucene.search.Weight$DefaultBulkScorer.score(Weight.java:166)
        at org.apache.lucene.search.BooleanScorer$1.score(BooleanScorer.java:59)
        at org.apache.lucene.search.BooleanScorer$BulkScorerAndDoc.score(BooleanScorer.java:90)
        at org.apache.lucene.search.BooleanScorer.scoreWindowSingleScorer(BooleanScorer.java:313)
        at org.apache.lucene.search.BooleanScorer.scoreWindow(BooleanScorer.java:336)
        at org.apache.lucene.search.BooleanScorer.score(BooleanScorer.java:364)
        at org.apache.lucene.search.BulkScorer.score(BulkScorer.java:39)
        at org.apache.lucene.search.IndexSearcher.search(IndexSearcher.java:821)
        at org.apache.lucene.search.IndexSearcher$5.call(IndexSearcher.java:763)
        at org.apache.lucene.search.IndexSearcher$5.call(IndexSearcher.java:760)
        at java.util.concurrent.FutureTask.run(FutureTask.java:266)

Looks like

MultiCollector.removeCollector(i)

is called on line 176, the loop:

for (LeafCollector c : collectors) {
        c.setScorer(scorer);
}

in setScorer can still step on it, on line 155.

I am however, unable to reproduce that with a unit test.

I made a copy of this class and added a null check in setScorer() and the problem goes away.