[OAK-1482] ConcurrentModificationException in FileStore

• Type: Bug
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Affects Version/s: 0.17
• Fix Version/s: 0.18
• Component/s: core
• Assignee: Jukka Zitting
• Reporter: Chetan Mehrotra
• Created: 28/Feb/14 14:44
• Updated: 11/Mar/14 09:51
• Resolved: 28/Feb/14 16:55

Description

At times with load ConcurrentModificationException is being seen in FileStore

Caused by: java.util.ConcurrentModificationException: null
	at java.util.LinkedList$ListItr.checkForComodification(LinkedList.java:953)
	at java.util.LinkedList$ListItr.next(LinkedList.java:886)
	at org.apache.jackrabbit.oak.plugins.segment.file.FileStore.loadSegment(FileStore.java:285)
	at org.apache.jackrabbit.oak.plugins.segment.AbstractStore.readSegment(AbstractStore.java:85)
	at org.apache.jackrabbit.oak.plugins.segment.Segment.getSegment(Segment.java:266)
	at org.apache.jackrabbit.oak.plugins.segment.Record.getSegment(Record.java:109)
	at org.apache.jackrabbit.oak.plugins.segment.BlockRecord.read(BlockRecord.java:52)
	at org.apache.jackrabbit.oak.plugins.segment.SegmentStream.read(SegmentStream.java:163)
	at com.google.common.io.ByteStreams.read(ByteStreams.java:828)
	at com.google.common.io.ByteStreams.readFully(ByteStreams.java:695)
	at org.apache.jackrabbit.oak.plugins.index.lucene.OakDirectory$OakIndexFile.loadBlob(OakDirectory.java:174)

Looking at the code of FileStore[1] in writeSegment call the list of data/bulk files gets modified. This method is marked as synchronized but other methods loadSegment are not synchronized. This might cause the iterators to fail. Probably using CopyOnWriteArrayList would help

https://github.com/apache/jackrabbit-oak/blob/trunk/oak-core/src/main/java/org/apache/jackrabbit/oak/plugins/segment/file/FileStore.java#L301