ArrayIndexOutOfBoundsException when iterating over TermDocs [LUCENE-2666]

A user got this very strange exception, and I managed to get the index that it happens on. Basically, iterating over the TermDocs causes an AAOIB exception. I easily reproduced it using the FieldCache which does exactly that (the field in question is indexed as numeric). Here is the exception:

Exception in thread "main" java.lang.ArrayIndexOutOfBoundsException: 114
at org.apache.lucene.util.BitVector.get(BitVector.java:104)
at org.apache.lucene.index.SegmentTermDocs.next(SegmentTermDocs.java:127)
at org.apache.lucene.search.FieldCacheImpl$LongCache.createValue(FieldCacheImpl.java:501)
at org.apache.lucene.search.FieldCacheImpl$Cache.get(FieldCacheImpl.java:183)
at org.apache.lucene.search.FieldCacheImpl.getLongs(FieldCacheImpl.java:470)
at TestMe.main(TestMe.java:56)

It happens on the following segment: _26t docCount: 914 delCount: 1 delFileName: _26t_1.del

And as you can see, it smells like a corner case (it fails for document number 912, the AIOOB happens from the deleted docs). The code to recreate it is simple:

FSDirectory dir = FSDirectory.open(new File("index"));
IndexReader reader = IndexReader.open(dir, true);

IndexReader[] subReaders = reader.getSequentialSubReaders();
for (IndexReader subReader : subReaders) {
Field field = subReader.getClass().getSuperclass().getDeclaredField("si");
field.setAccessible(true);
SegmentInfo si = (SegmentInfo) field.get(subReader);
System.out.println("--> " + si);
if (si.getDocStoreSegment().contains("_26t")) {
// this is the probleatic one...
System.out.println("problematic one...");
FieldCache.DEFAULT.getLongs(subReader, "__documentdate", FieldCache.NUMERIC_UTILS_LONG_PARSER);
}
}

Here is the result of a check index on that segment:

8 of 10: name=_26t docCount=914
compound=true
hasProx=true
numFiles=2
size (MB)=1.641
diagnostics = {optimize=false, mergeFactor=10, os.version=2.6.18-194.11.1.el5.centos.plus, os=Linux, mergeDocStores=true, lucene.version=3.0.2 953716 - 2010-06-11 17:13:53, source=merge, os.arch=amd64, java.version=1.6.0, java.vendor=Sun Microsystems Inc.}
has deletions [delFileName=_26t_1.del]
test: open reader.........OK [1 deleted docs]
test: fields..............OK [32 fields]
test: field norms.........OK [32 fields]
test: terms, freq, prox...ERROR [114]
java.lang.ArrayIndexOutOfBoundsException: 114
at org.apache.lucene.util.BitVector.get(BitVector.java:104)
at org.apache.lucene.index.SegmentTermDocs.next(SegmentTermDocs.java:127)
at org.apache.lucene.index.SegmentTermPositions.next(SegmentTermPositions.java:102)
at org.apache.lucene.index.CheckIndex.testTermIndex(CheckIndex.java:616)
at org.apache.lucene.index.CheckIndex.checkIndex(CheckIndex.java:509)
at org.apache.lucene.index.CheckIndex.checkIndex(CheckIndex.java:299)
at TestMe.main(TestMe.java:47)
test: stored fields.......ERROR [114]
java.lang.ArrayIndexOutOfBoundsException: 114
at org.apache.lucene.util.BitVector.get(BitVector.java:104)
at org.apache.lucene.index.ReadOnlySegmentReader.isDeleted(ReadOnlySegmentReader.java:34)
at org.apache.lucene.index.CheckIndex.testStoredFields(CheckIndex.java:684)
at org.apache.lucene.index.CheckIndex.checkIndex(CheckIndex.java:512)
at org.apache.lucene.index.CheckIndex.checkIndex(CheckIndex.java:299)
at TestMe.main(TestMe.java:47)
test: term vectors........ERROR [114]
java.lang.ArrayIndexOutOfBoundsException: 114
at org.apache.lucene.util.BitVector.get(BitVector.java:104)
at org.apache.lucene.index.ReadOnlySegmentReader.isDeleted(ReadOnlySegmentReader.java:34)
at org.apache.lucene.index.CheckIndex.testTermVectors(CheckIndex.java:721)
at org.apache.lucene.index.CheckIndex.checkIndex(CheckIndex.java:515)
at org.apache.lucene.index.CheckIndex.checkIndex(CheckIndex.java:299)
at TestMe.main(TestMe.java:47)

The creation of the index does not do something fancy (all defaults), though there is usage of the near real time aspect (IndexWriter#getReader) which does complicate deleted docs handling. Seems like the deleted docs got written without matching the number of docs?. Sadly, I don't have something that recreates it from scratch, but I do have the index if someone want to have a look at it (mail me directly and I will provide a download link).

I will continue to investigate why this might happen, just wondering if someone stumbled on this exception before. Lucene 3.0.2 is used.

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Migrated from [LUCENE-2666](https://issues.apache.org/jira/browse/LUCENE-2666) by Shay Banon (@kimchy), 1 vote, updated Feb 07 2011
Attachments: [checkindex-out.txt](https://apache.github.io/lucene-jira-archive/attachments/LUCENE-2666/checkindex-out.txt)