Batch Insertions with Hibernate & Spring

Question

My application is based on Hibernate 3.2 and Spring 2.5. Here is the transaction management related snippet from the application context:

  <tx:annotation-driven transaction-manager="txManager"/>
    <bean id="txManager" class="org.springframework.orm.hibernate3.HibernateTransactionManager">
          <property name="sessionFactory" ref="sessionFactory"/>
          <property name="nestedTransactionAllowed" value="true"/> 
    </bean> 
    <bean id="transactionTemplate"  classs="org.springframework.transaction.support.TransactionTemplate">
           <property name="transactionManager" ref="txManager"/>
    </bean>
    <bean class="org.springframework.beans.factory.annotation.RequiredAnnotationBeanPostProcessor"/>
    <bean id="sessionFactory" class="org.springframework.orm.hibernate3.annotation.AnnotationSessionFactoryBean">
    <property name="configLocation" value="classpath:/hibernate.cfg.xml"></property>
    </bean>

For all the DAO's there are relevant Service class and the transactions are handled there using @Transactional on each method in the service layer. However there is a scenario now that a method in DAO say "parse()" is called from the service layer. In the service layer I specified @Transactional(readOnly=false). This parse method in the DAO calls another method say "save()" in the same DAO which stores a large number of rows (around 5000) in the database. Now the save method is called in a loop from the parse function. Now the issue is that after around 100 calls to the "save" method.. i sometimes get a OutOfMemory Exception or sometimes the program stops responding.

For now these are the changes which I have made to the save method:

Session session = getHibernateTemplate().getSessionFactory().openSession();
            Transaction tx = session.beginTransaction();

            int counter = 0;
            if(books!=null && !books.isEmpty()){
                for (Iterator iterator = books.iterator(); iterator
                        .hasNext();) {
                    Book book = (Book) iterator.next();
                    session.save(book);
                    counter++;
                    if(counter % 20==0) {
                         session.flush();
                         session.clear();
                    }
                }
            }
            tx.commit();
        session.close();

This is the only method in my application where I start a transaction like this and commit it at the end of method. Otherwise I normally just call getHibernateTemplate.save(). I am not sure whether I should perform transaction management for this save method separately in the DAO by placing @Transactional(readOnly=false, PROPOGATION=NEW) on save(), or is this approach okay?

Also I have updated the hibernate.jdbc.batch_size to 20 in the hibernate.cfg configuration file.

Any suggestions?

Answer 1

For the batch insertion with hibernate, the best practice is StatelessSession, it doesn`t cache any states of your entity, you will not encounter OutOfMemory, the code like:

if (books == null || books.isEmpty) {
    return;
}
StatelessSession session = getHibernateTemplate().getSessionFactory().openStatelessSession();
Transaction tx = session.beginTransaction();

for (Book each : books) {           
    session.insert(book);           
}
tx.commit();
session.close();

And the Transaction of StatelessSession is independent from the current transaction context.