Optimistic Lock problem occurring

Solution In Progress - Updated -

Environment

  • Red Hat JBoss Fuse
    • 6.1.0

Issue

  • Optimistic Lock problem occurring when using OpenJPA
  • When trying to flush an OpenJPA EntityManager the following exception is thrown:
<openjpa-2.3.0-r422266:1540826 fatal store error> org.apache.openjpa.persistence.OptimisticLockException: Optimistic locking errors were detected when flushing to the data store.  The following objects may have been concurrently modified in another transaction: [com.example.domain.ModelClass-2016001]
        at org.apache.openjpa.kernel.BrokerImpl.newFlushException(BrokerImpl.java:2359)
        at org.apache.openjpa.kernel.BrokerImpl.flush(BrokerImpl.java:2207)
        at org.apache.openjpa.kernel.BrokerImpl.flushSafe(BrokerImpl.java:2105)
        at org.apache.openjpa.kernel.BrokerImpl.flush(BrokerImpl.java:1876)
        at org.apache.openjpa.kernel.DelegatingBroker.flush(DelegatingBroker.java:1045)
        at org.apache.openjpa.persistence.EntityManagerImpl.flush(EntityManagerImpl.java:663)
        at org.apache.aries.jpa.container.impl.EntityManagerWrapper.flush(EntityManagerWrapper.java:117)
        at org.apache.aries.jpa.container.context.transaction.impl.JTAEntityManager.flush(JTAEntityManager.java:218)
...

Resolution

When using JPA, you should refresh the object to be saved first, using entityManager.refresh(ModelClass), then update it and only then merge and flush it.

For example:

TypedQuery query = entityManager.createNamedQuery("ModelClass.getId", ModelClass.class);
query.setParameter("id", 10);
ModelClass modelClass = (ModelClass) query.getSingleResult();

entityManager.refresh(modelClass);
modelClass.setTimestamp(new Timestamp(System.currentTimeMillis()));
entityManager.merge(modelCLass);
entityManager.flush();

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