Hibernate: Two Connections for one call???

[ttmrb]

We are currently debugging a puzzling problem with our database connection pool. It seems that whenever one we make a call to our database, two database connections are checked out of our connection pool. We are having a hard time tracking down what portion of our application might be causing this. We have a spring based application that has DAOs that use the older Spring HibernateTemplate as well as the Spring HibernateTransactionManager and the @Transactional annotation. We are using Hibernate 3.3.1 and c3p0 as our connection pool. We are wondering if there is any sort of configuration that might cause two sessions to be created and therefore, two connections be checked out? Thanks.

[Marten Deinum]

Well how about some configuration and code (web.xml, applicationContext etc.).

[ttmrb]

Most certainly. Here are the Spring bean configurations for our Hibernate setup. I have removed some of the repetitive configuration settings to keep the size down. My worry is the use of the session factory more than once. If Hibernate is set up to do session per request and we use the session factory twice, would that not create more than once session, and in turn, more than one database connection?

<bean id="dataSource" class="com.mchange.v2.c3p0.ComboPooledDataSource" destroy-method="close">
  <property name="driverClass"> <value>com.mysql.jdbc.Driver</value></property>
<property name="jdbcUrl"> <value>...</value> </property>
<property name="user"> <value>...</value> </property>
<property name="password"> <value>...</value></property>
<property name="acquireIncrement"><value>10</value></property>
<property name="idleConnectionTestPeriod"><value>300</value></property>
<property name="minPoolSize"><value>10</value></property>
<property name="maxPoolSize"><value>100</value></property>
<property name="maxStatements"><value>0</value></property>
<property name="maxIdleTime"><value>10800</value></property>
</bean>

<bean id="sessionFactory"
    class="org.springframework.orm.hibernate3.LocalSessionFactoryBean">
    <property name="dataSource" ref="dataSource" />
        <property name="mappingResources">
        <list>
          ... Hibernate HBM files ...
        </list>
    </property>
    <property name="hibernateProperties">
        <props>
          <prop key="hibernate.dialect">org.hibernate.dialect.MySQLDialect</prop>
<prop key="hibernate.show_sql">false</prop>
<prop key="hibernate.format_sql">false</prop>
        </props>            
    </property>
</bean>
	
<tx:annotation-driven transaction-manager="transactionManager"/>

<bean id="transactionManager" class="org.springframework.orm.hibernate3.HibernateTransactionManager">
    <property name="sessionFactory">
      <ref local="sessionFactory"/>
    </property>
</bean>
	 
<bean id="proxyStore" class="net.sf.gilead.core.store.stateless.StatelessProxyStore" />

<bean id="persistenceUtil" class="net.sf.gilead.core.hibernate.spring.HibernateSpringUtil">
    <property name="sessionFactory" ref="sessionFactory"/>
</bean>								     

<bean id="persistentBeanManager" class="net.sf.gilead.core.PersistentBeanManager">
    <property name="proxyStore" ref="proxyStore" />
    <property name="persistenceUtil" ref="persistenceUtil" />
</bean>

Thanks!

[Marten Deinum]

For some reason seeing something like HibernateSpringUtil makes me shudder... Why on earth would you need that. Also you left out the properties and those can be quite interesting... (The same goes for your HibernateSpringUtil and how you use/call this class).

[ttmrb]

I have added some additional code to my previous post for more details.

The HibernateSpringUtil is from Gilead. This enables us to use hibernate enabled objects in GWT. When a hibernate enabled object is transferred over to the client the hibernate specific stuff is stripped away and re-attached when it comes back to the server.

Hope this helps.

[Marten Deinum]

There seems nothing wrong with your configuration so there must be something weird going on. Do you have duplicate instances of beans (maybe by accident)? Can you post your data usage code.