[TAP5-2499] Race condition in EntityManagerSource#getEntityManagerFactory

• Type: Bug
• Status: Resolved
• Priority: Major
• Resolution: Fixed
• Affects Version/s: 5.4, 5.3.8
• Fix Version/s: 5.4.1
• Component/s: tapestry-jpa
• Assignee: Kalle Korhonen
• Reporter: Dmitry Gusev
• Created: 07/Sep/15 09:51
• Updated: 15/Mar/16 00:09
• Resolved: 14/Mar/16 22:10

Description

On application start if more than one thread needs an entity manager more than one instance of EntityManagerFactory may be created.

This is undesirable, because EMF may use a connection pool and creating more than one instance will lead to too many open database connections.

EntityManagerSourceImpl.java:

    public EntityManagerFactory getEntityManagerFactory(final String persistenceUnitName)
    {
        EntityManagerFactory emf = entityManagerFactories.get(persistenceUnitName);

        if (emf == null)
        {
            emf = createEntityManagerFactory(persistenceUnitName);

            entityManagerFactories.put(persistenceUnitName, emf);
        }

        return emf;
    }

Above code needs some synchronization.