public void saveOrUpdate(Object dataHierarchyRoot) {
    final EntityManager entityManager = entityManagerFactory.createEntityManager();
    final EntityTransaction transaction = entityManager.getTransaction();

    try {
        transaction.begin();

        // This single call may result in inserting up to 10K records
        entityManager.merge(dataHierarchyRoot);
        transaction.commit();
    } catch (final Throwable e) {
        // error handling redacted for brevity
    } finally {
        entityManager.close();
    }
}

for (Object entity: entities) {
    if(entity.getId() == null) {
        entityManager.persist(entity);
    } else {
        entityManager.merge(entity);
    }
    if ((i % batchSize) == 0) {
        entityManager.getTransaction().commit();
        entityManager.clear();
        entityManager.getTransaction().begin();
    }
}
entityManager.getTransaction().commit();
em.getTransaction().commit();

<persistence-unit name="pu" transaction-type="RESOURCE_LOCAL">
    <provider>org.hibernate.ejb.HibernatePersistence</provider>
        <properties>
            <property name="hibernate.dialect" value="org.hibernate.dialect.OracleDialect"/>
            <property name="hibernate.connection.username" value="***"/>
            <property name="hibernate.connection.password" value="***"/>
            <property name="hibernate.connection.driver_class" value="oracle.jdbc.OracleDriver"/>
            <property name="hibernate.connection.url" value="jdbc:oracle:thin:@***"/>
            <property name="hibernate.jdbc.batch_size" value="100"/>
        </properties>
    </persistence-unit>

Session session = SessionFactory.openSession();
Transaction tx = session.beginTransaction();
for ( int i=0; i<100000; i++ ) {
    Employee employee = new Employee(.....);
    session.save(employee);
}
tx.commit();
session.close();