[AMQ-3160] ConcurrentModificationException in ActiveMQ Journal Checkpoint Worker

• Type: Bug
• Status: Resolved
• Priority: Minor
• Resolution: Fixed
• Affects Version/s: 5.4.2
• Fix Version/s: 5.5.0
• Component/s: Message Store

Environment

CentOS 5.2

• Assignee: Gary Tully
• Reporter: Craig Condit
• Created: 25/Jan/11 22:50
• Updated: 26/Jan/11 12:15
• Resolved: 26/Jan/11 12:15

Description

There appears to be a race condition accessing Journal.getHashMap() from the ActiveMQ Journal Checkpoint Worker thread. Under high loads, we occasionally see the following exception in our logs:

Exception in thread "ActiveMQ Journal Checkpoint Worker" java.util.ConcurrentModificationException
at java.util.HashMap$HashIterator.nextEntry(HashMap.java:793)
at java.util.HashMap$EntryIterator.next(HashMap.java:834)
at java.util.HashMap$EntryIterator.next(HashMap.java:832)
at java.util.AbstractMap.putAll(AbstractMap.java:255)
at java.util.TreeMap.putAll(TreeMap.java:304)
at java.util.TreeMap.<init>(TreeMap.java:162)
at org.apache.kahadb.journal.Journal.getFileMap(Journal.java:660)
at org.apache.activemq.store.kahadb.MessageDatabase.checkpointUpdate(MessageDatabase.java:970)
at org.apache.activemq.store.kahadb.MessageDatabase.access$400(MessageDatabase.java:82)
at org.apache.activemq.store.kahadb.MessageDatabase$9.execute(MessageDatabase.java:599)
at org.apache.kahadb.page.Transaction.execute(Transaction.java:728)
at org.apache.activemq.store.kahadb.MessageDatabase.checkpointCleanup(MessageDatabase.java:597)
at org.apache.activemq.store.kahadb.MessageDatabase$3.run(MessageDatabase.java:249)

This leads to the thread aborting prematurely.

Issue Links

• is related to: AMQ-3161 Race condition in ActiveMQ Journal Checkpoint worker thread cleanup leads to multiple running instances