[CAY-2713] ConcurrentModificationException when Inserting

• Type: Bug
• Status: Closed
• Priority: Blocker
• Resolution: Fixed
• Affects Version/s: 4.2.M3
• Fix Version/s: 4.2.B1
• Assignee: Nikita Timofeev
• Reporter: Peter Hvass
• Created: 18/Jun/21 06:26
• Updated: 08/Sep/21 11:03
• Resolved: 21/Jun/21 11:46

Description

We're seeing an odd CoModException when recording visit information on our web app - we assemble information related to the visit (i.e.: page visited, date of visit) and then commit. Vast majority of cases this works except a rare few where we see the following stack trace.

Always thankful for this project and its maintenance - if there is anything I can do to help debug or provide further info please just let me know.

Stack Trace:
java.util.ConcurrentModificationException
at java.util.HashMap.forEach(HashMap.java:1292)
at org.apache.cayenne.access.flush.operation.Values.merge(Values.java:90)
at org.apache.cayenne.access.flush.operation.DbRowOpMerger.mergeValues(DbRowOpMerger.java:75)
at org.apache.cayenne.access.flush.operation.DbRowOpMerger.visitInsert(DbRowOpMerger.java:49)
at org.apache.cayenne.access.flush.operation.DbRowOpMerger.visitInsert(DbRowOpMerger.java:29)
at org.apache.cayenne.access.flush.operation.InsertDbRowOp.accept(InsertDbRowOp.java:40)
at org.apache.cayenne.access.flush.operation.DbRowOpMerger.apply(DbRowOpMerger.java:41)
at org.apache.cayenne.access.flush.operation.DbRowOpMerger.apply(DbRowOpMerger.java:29)
at java.util.HashMap.merge(HashMap.java:1254)
at org.apache.cayenne.access.flush.DefaultDataDomainFlushAction.lambda$mergeSameObjectIds$2(DefaultDataDomainFlushAction.java:133)
at java.util.ArrayList.forEach(ArrayList.java:1257)
at org.apache.cayenne.access.flush.DefaultDataDomainFlushAction.mergeSameObjectIds(DefaultDataDomainFlushAction.java:133)
at org.apache.cayenne.access.flush.DefaultDataDomainFlushAction.flush(DefaultDataDomainFlushAction.java:85)
at org.apache.cayenne.access.DataDomain.onSyncFlush(DataDomain.java:637)
at org.apache.cayenne.access.DataDomain.onSyncNoFilters(DataDomain.java:609)
at org.apache.cayenne.access.DataDomain$DataDomainSyncFilterChain.onSync(DataDomain.java:835)
at org.apache.cayenne.tx.TransactionFilter.lambda$onSync$0(TransactionFilter.java:61)
at org.apache.cayenne.tx.DefaultTransactionManager$BaseTransactionHandler.performInTransaction(DefaultTransactionManager.java:180)
at org.apache.cayenne.tx.DefaultTransactionManager$BaseTransactionHandler.performInNewTransaction(DefaultTransactionManager.java:152)
at org.apache.cayenne.tx.DefaultTransactionManager$NestedTransactionHandler.handle(DefaultTransactionManager.java:95)
at org.apache.cayenne.tx.DefaultTransactionManager.performInTransaction(DefaultTransactionManager.java:62)
at org.apache.cayenne.tx.DefaultTransactionManager.performInTransaction(DefaultTransactionManager.java:40)
at org.apache.cayenne.tx.TransactionFilter.onSync(TransactionFilter.java:61)
at org.apache.cayenne.access.DataDomain$DataDomainSyncFilterChain.onSync(DataDomain.java:834)
at org.apache.cayenne.access.DataDomain.onSync(DataDomain.java:596)
at org.apache.cayenne.access.DataContext.flushToParent(DataContext.java:737)
[wrapped] org.apache.cayenne.CayenneRuntimeException: [v.4.2.M3 Mar 13 2021 14:15:14] Commit Exception
at org.apache.cayenne.access.DataContext.flushToParent(DataContext.java:769)
at org.apache.cayenne.access.DataContext.commitChanges(DataContext.java:686)