My spring+hibernate app does not closes jdbc connections

Question

I have an Spring+Hibernate+Tomcat+MySql application in production, I'm running into a problem. I think the application is not closing it's jdbc connections, and when it reaches its limits (currently 200), the application stop responding, and I have to restart tomcat. Do I need to close this connections somewhere ? Here is my Datasource:

<?xml version="1.0" encoding="UTF-8"?>
<Context path="/" override="true" reloadable="false" swallowOutput="false">
    <!-- jdbcInterceptors, removeAbandoned, removeAbandonedTimeout van juntos, ver http://www.tomcatexpert.com/blog/2012/01/24/using-tomcat-7-jdbc-\
    connection-pool-production, y https://tomcat.apache.org/tomcat-7.0-doc/jdbc-pool.html -->
    <!-- removeAbandonedTimeout es en segundos -->

    <Resource name="jdbc/catWDB" auth="Container" type="javax.sql.DataSource"
              driverClassName="com.mysql.jdbc.Driver"
              factory="org.apache.tomcat.dbcp.dbcp.BasicDataSourceFactory"
              url="@URL@"
              username="@USERNAME@"
              password="@PASSWORD@"

              maxActive="200"
              maxIdle="50"
              minIdle="10"
              suspectTimeout="60"
              timeBetweenEvictionRunsMillis="30000"
              minEvictableIdleTimeMillis="60000"

              validationQuery="select 1"
              validationInterval="30000"
              testOnBorrow="true"

              removeAbandoned="true"
              removeAbandonedTimeout="60"
              abandonWhenPercentageFull="10"
              maxWait="10000"

              jdbcInterceptors="ResetAbandonedTimer;StatementFinalizer"


            />

</Context>

And here is an image of the appdynamics monitoring the connections, from 3 days until now

Here is a excerpt of the error I get on the catalina.out log file:

type Exception report

message Request processing failed; nested exception is org.hibernate.exception.JDBCConnectionException: Cannot open connection

description The server encountered an internal error that prevented it from fulfilling this request.

exception

org.springframework.web.util.NestedServletException: Request processing failed; nested exception is org.hibernate.exception.JDBCConnectionException: Cannot open connection org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:932) org.springframework.web.servlet.FrameworkServlet.doGet(FrameworkServlet.java:816) javax.servlet.http. . . .

root cause

org.hibernate.exception.JDBCConnectionException: Cannot open connection org.hibernate.exception.SQLStateConverter.convert(SQLStateConverter.java:99) org.hibernate.exception.JDBCExceptionHelper.convert(JDBCExceptionHelper.java:66) org.hibernate.exception.JDBCExceptionHelper.convert(JDBCExceptionHelper.java:52) org.hibernate.jdbc.ConnectionManager. . . .

root cause

com.mysql.jdbc.exceptions.jdbc4.MySQLNonTransientConnectionException: Too many connections sun.reflect.GeneratedConstructorAccessor67.newInstance(Unknown Source) sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:27) java.lang.reflect.Constructor.newInstance(Constructor.java:513) com.mysql.jdbc.Util.handleNewInstance(Util.java:406) com.mysql.jdbc.Util.getInstance(Util.java:381) com.mysql.jdbc.SQLError.

UPDATE

public Category findByIdByApp(Integer id, int appListId) throws DataAccessException {

       Criteria criteria = getSession().createCriteria(Category.class,"category")
                .createAlias("appList", "app")
                .add(Restrictions.and(Restrictions.eq("category.categoryId", id), Restrictions.eq("app.appListId", appListId)));
          List result=criteria.list();

        if(result.size()==1)

                return (Category) result.get(0);
         else
                return null;
    }

The Category domain object is mapped like this:

@Entity
@Table(name = "category")
public class Category implements Comparable, Serializable {

So my guess is, taking mithridas comments into account, that I´m using the hibernate session´s manually, And I would need to close them with something like this:

this.getSession().clear();

Or i could implement @PersistenceContext. Would anyone direct me to this implementations so I can evaluate which is best for us to use ?

Thank you.

UPDATE2: Added more info in answer to James Massey comment:

These are my: datasource, sessionFactory, transactionManager, and categoryDAO sessionFactory assignment:

<!-- ========================= DATA ACCESS OBJECT DEFINITIONS ======================== -->

<bean id="dataSource"
      class="org.springframework.jndi.JndiObjectFactoryBean">
    <property name="jndiName">
        <value>java:comp/env/jdbc/catWDB</value>
    </property>
</bean>


<bean id="sessionFactory" class="org.springframework.orm.hibernate3.LocalSessionFactoryBean">
    <property name="dataSource">
        <ref local="dataSource"/>
    </property>
    <property name="configLocation" value="classpath:hibernate.cfg.xml" />

    <property name="hibernateProperties">
        <props>
            <prop key="hibernate.dialect">org.hibernate.dialect.MySQLDialect</prop>
            <prop key="hibernate.connection.pool_size">3</prop>
            <prop key="hibernate.show_sql">true</prop>
            <prop key="hibernate.max_fetch_depth">1</prop>

        </props>
    </property>
</bean>


<!---->
<bean id="transactionManager" lazy-init="true"
      class="org.springframework.orm.hibernate3.HibernateTransactionManager">
    <property name="sessionFactory">
        <ref local="sessionFactory"/>
    </property>

</bean>



<bean id="categoryDAOTarget" class="com.bamboo.catW3.DAO.impl.CategoryDAOImpl">
    <property name="sessionFactory">
        <ref local="sessionFactory"/>
    </property>
</bean>

Answer 1

The problem did not lay in the sessions but in the connection pool, sessions where being managed correctly, but the connection pool in the JDBC layer wasn't closing the connections.

These are the things that I did to fix them.

JDBC context configuration

1.- Changed the JDBC connection factory from tomcat's old BasicDataSourceFactory to tomcat's new DataSourceFactory

2.- Tuned the JDBC settings based on this article: http://www.tomcatexpert.com/blog/2010/04/01/configuring-jdbc-pool-high-concurrency

Session factory xml configuration

3.- Deleted this line from the session factory configuration:

<prop key="hibernate.max_fetch_depth">1</prop>

This is how my configuration ended up:

JDBC context configuration

<?xml version="1.0" encoding="UTF-8"?>
<Context path="/" override="true" reloadable="false" swallowOutput="false">
    <Resource name="jdbc/catWDB" auth="Container" type="javax.sql.DataSource"
              driverClassName="com.mysql.jdbc.Driver"
              factory="org.apache.tomcat.jdbc.pool.DataSourceFactory"
              url="@URL@"
              username="@USERNAME@"
              password="@PASSWORD@"
              maxActive="200"
              maxIdle="50"
              minIdle="10"
              suspectTimeout="60"
              timeBetweenEvictionRunsMillis="30000"
              minEvictableIdleTimeMillis="60000"
              validationQuery="select 1"
              validationInterval="30000"
              testOnBorrow="true"
              removeAbandoned="true"
              removeAbandonedTimeout="60"
              abandonWhenPercentageFull="10"
              maxWait="10000"
              jdbcInterceptors="ResetAbandonedTimer;StatementFinalizer"
            />
</Context>

Session factory xml configuration

<bean id="sessionFactory" class="org.springframework.orm.hibernate3.LocalSessionFactoryBean">
        <property name="dataSource">
            <ref local="dataSource"/>
        </property>
        <property name="configLocation" value="classpath:hibernate.cfg.xml" />
        <property name="hibernateProperties">
            <props>
                <prop key="hibernate.dialect">org.hibernate.dialect.MySQLDialect</prop>
                <prop key="hibernate.show_sql">false</prop>
                <prop key="hibernate.max_fetch_depth">3</prop>
            </props>
        </property>
</bean>

Answer 2

I think you should use @PersistenceContext annotation to obtain EntityManager from Spring context and @Transactional annotation to drive your transactions. This way you won't need to worry about closing Hibernate sessions manually, and number of connections will not increase until there are too many connections.