see:
http://www.nabble.com/AMQ-Journal-data-files-never-deleted-to16728103s2354.html#a16728103
Exception is:
Exception in thread "ActiveMQ Scheduler" java.util.ConcurrentModificationException
at java.util.HashMap$HashIterator.nextEntry(HashMap.java:787)
at java.util.HashMap$KeyIterator.next(HashMap.java:823)
at java.util.AbstractSet.removeAll(AbstractSet.java:143)
at org.apache.activemq.kaha.impl.async.AsyncDataManager.consolidateDataFilesNotIn(AsyncDataManager.java:404)
at org.apache.activemq.store.amq.AMQPersistenceAdapter.cleanup(AMQPersistenceAdapter.java:417)
at org.apache.activemq.store.amq.AMQPersistenceAdapter$3.run(AMQPersistenceAdapter.java:269)
at org.apache.activemq.thread.SchedulerTimerTask.run(SchedulerTimerTask.java:33)
at java.util.TimerThread.mainLoop(Timer.java:512)
at java.util.TimerThread.run(Timer.java:462)