Major Description
I've been iterating with Tom on this corruption that CheckIndex detects in his rather large index (720 GB in a single segment):
java -Xmx16G -Xms16G -cp $JAR -ea:org.apache.lucene... org.apache.lucene.index.CheckIndex /XXXX/shards/4/core-1/data/test_index -verbose 2>&1 |tee -a shard4_reoptimizedNewJava
Opening index @ /htsolr/lss-reindex/shards/4/core-1/data/test_index
Segments file=segments_e numSegments=1 version=4.10.2 format= userData={commitTimeMSec=1421479358825}
1 of 1: name=_8m8 docCount=1130856
version=4.10.2
codec=Lucene410
compound=false
numFiles=10
size (MB)=719,967.32
diagnostics = {timestamp=1421437320935, os=Linux, os.version=2.6.18-400.1.1.el5, mergeFactor=2, source=merge, lucene.version=4.10.2, os.arch=amd64, mergeMaxNumSegments=1, java.version=1.7.0_71, java.vendor=Oracle Corporation}
no deletions
test: open reader.........OK
test: check integrity.....OK
test: check live docs.....OK
test: fields..............OK [80 fields]
test: field norms.........OK [23 fields]
test: terms, freq, prox...ERROR: java.lang.AssertionError: -96
java.lang.AssertionError: -96
at org.apache.lucene.codecs.lucene41.ForUtil.skipBlock(ForUtil.java:228)
at org.apache.lucene.codecs.lucene41.Lucene41PostingsReader$BlockDocsAndPositionsEnum.skipPositions(Lucene41PostingsReader.java:925)
at org.apache.lucene.codecs.lucene41.Lucene41PostingsReader$BlockDocsAndPositionsEnum.nextPosition(Lucene41PostingsReader.java:955)
at org.apache.lucene.index.CheckIndex.checkFields(CheckIndex.java:1100)
at org.apache.lucene.index.CheckIndex.testPostings(CheckIndex.java:1357)
at org.apache.lucene.index.CheckIndex.checkIndex(CheckIndex.java:655)
at org.apache.lucene.index.CheckIndex.main(CheckIndex.java:2096)
test: stored fields.......OK [67472796 total field count; avg 59.665 fields per doc]
test: term vectors........OK [0 total vector count; avg 0 term/freq vector fields per doc]
test: docvalues...........OK [0 docvalues fields; 0 BINARY; 0 NUMERIC; 0 SORTED; 0 SORTED_NUMERIC; 0 SORTED_SET]
FAILED
WARNING: fixIndex() would remove reference to this segment; full exception:
java.lang.RuntimeException: Term Index test failed
at org.apache.lucene.index.CheckIndex.checkIndex(CheckIndex.java:670)
at org.apache.lucene.index.CheckIndex.main(CheckIndex.java:2096)
WARNING: 1 broken segments (containing 1130856 documents) detected
WARNING: would write new segments file, and 1130856 documents would be lost, if -fix were specified
And Rob spotted long -> int casts in our skip list writers that look like they could cause such corruption if a single high-freq term with many positions required > 2.1 GB to write its positions into .pos.