Why is Hibernate blocking Java process to exit?

Question

And how do I avoid it?

This is the code I have:

persistence.xml

<?xml version="1.0" encoding="UTF-8"?>
<persistence xmlns="http://xmlns.jcp.org/xml/ns/persistence"
             xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
             xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/persistence
                                 http://xmlns.jcp.org/xml/ns/persistence/persistence_2_1.xsd"
             version="2.1">
    <persistence-unit name="testdb" transaction-type="RESOURCE_LOCAL">
        <provider>org.hibernate.jpa.HibernatePersistenceProvider</provider>
        <properties>
            <property name="hibernate.connection.driver_class" value="org.h2.Driver"/>
            <property name="hibernate.connection.url" value="jdbc:h2:tcp://localhost:9092/~/h2dbs/testdb"/>
            <property name="hibernate.connection.username" value="sa"/>
            <property name="hibernate.connection.password" value=""/>
            <property name="hibernate.connection.useUnicode" value="true"/>
            <property name="hibernate.connection.characterEncoding" value="utf-8"/>
            <property name="hibernate.show_sql" value="false"/>
        </properties>
    </persistence-unit>
</persistence>

PersistenceUtil.java

public class PersistenceUtil {

    private static EntityManagerFactory entityManagerFactory;

    static {
        entityManagerFactory = Persistence.createEntityManagerFactory("testdb");
    }

    public static EntityManager getEntityManager() {
        final EntityManager entityManager = entityManagerFactory.createEntityManager();
        return entityManager;
    }
}

and TestClass.java

public class TestClass {
    public static void main(String[] args) {
        final EntityManager em = PersistenceUtil.getEntityManager();
        final EntityTransaction transaction = em.getTransaction();
        transaction.begin();
        final TestTable testTable = new TestTable();
        testTable.setData("Sample Data");
        em.merge(testTable);
        transaction.commit();
        em.close();
    }
}

So when I run the main method in TestClass, I will see a row inserted in the DB with "Sample Data" fine, but the program will never exit, it will just hang..

I think Hibernate is creating a thread, but how do I avoid it?

Answer 1

try to close entityManagerFactory also ,in your PersistenceUtil just make additional method to close entityManagerFactory

 public class PersistenceUtil {

        private static EntityManagerFactory entityManagerFactory;

        static {
            entityManagerFactory = Persistence.createEntityManagerFactory("testdb");
        }

        public static EntityManager getEntityManager() {
            final EntityManager entityManager = entityManagerFactory.createEntityManager();
            return entityManager;
        }

    public static void closeEntityManagerFactory() {
           entityManagerFactory.close();
        }
    }




public class TestClass {
    public static void main(String[] args) {
        final EntityManager em = PersistenceUtil.getEntityManager();
        final EntityTransaction transaction = em.getTransaction();
        transaction.begin();
        final TestTable testTable = new TestTable();
        testTable.setData("Sample Data");
        em.merge(testTable);
        transaction.commit();
        em.close():
        PersistenceUtil.closeEntityManagerFactory()

    }
}

Answer 2

Can you try adding a method on PersistenceUtil called close that closes the EntityManagerFactory and see if the main thread completes