Database Connections Aren't Closing - mysql

Question

I'm using spring 3.0 (jdbcTemplate), Tomcat, MySQL and C3p0 to handle my database activities. I'm using both jdbctemplate and simplejdbctemplate which will take care of creating and closing connections, statements, resultsets etc. I'm using C3p0 for connection pooling however the connections are remaining open and eventually the app will run out of connections.
Here is the configuration of my data source:
<bean id="dataSource" class="com.mchange.v2.c3p0.ComboPooledDataSource" destroy-method="close" >
<property name="driverClass" value="${jdbc.driverClassName}"></property>
<property name="jdbcUrl" value="${jdbc.url}"></property>
<property name="user" value="${jdbc.username}"></property>
<property name="password" value="${jdbc.password}"></property>
<property name="initialPoolSize" value="5"></property>
<property name="maxPoolSize" value="100"/>
<property name="minPoolSize" value="5"/>
<property name="maxIdleTime" value="30"/>
<property name="maxIdleTimeExcessConnections" value="30"/>
<property name="maxConnectionAge" value="30"/>
<property name="checkoutTimeout" value="100"/>
<property name="maxStatements" value="50"></property>
<property name="automaticTestTable" value="C3P0_TEST_TABLE"></property>
<property name="testConnectionOnCheckin" value="true"></property>
<property name="idleConnectionTestPeriod" value="30"></property>
</bean>
I'm also using TransactionManagement provided by spring - here is the configuration of that:
<!-- enable the configuration of transactional behavior based on annotations -->
<tx:annotation-driven transaction-manager="txManager"/>
<bean id="txManager" class="org.springframework.jdbc.datasource.DataSourceTransactionManager">
<property name="dataSource" ref="dataSource"/>
</bean>
Here is the rest of the datasource configuration:
<bean id="simpleJdbcTemplate" class="org.springframework.jdbc.core.simple.SimpleJdbcTemplate">
<constructor-arg><ref bean="dataSource"/></constructor-arg>
</bean>
<bean id="userDAO" class="com.Test.dao.UserDAOImpl">
<property name="jdbcTemplate"><ref bean="jdbcTemplate"/></property>
</bean>
Finally here is a method where I update records into a database:
#Transactional(readOnly=false)
public void updateBenchMarkCumulative(List<BenchMarkCumulative> bmCumulativeList)
{
List<Object[]> parameters = new ArrayList<Object[]>();
for(BenchMarkCumulative bmCumulative : bmCumulativeList)
{
parameters.add(new Object[]{bmCumulative.getCumulativeAmt(), bmCumulative.getPkBenchMarkCumulative()});
}
this.simpleJdbcTemplate.batchUpdate(UPDATE_BENCHMARK_CUMULATIVE, parameters);
}
Is there something I'm doing wrong in my configuration or am I missing something that needs to be added to the configuration or coding?
Here is the exception being thrown:
INFO [http-8080-1] (AbstractPoolBackedDataSource.java510) - Initializing c3p0 pool... com.mchange.v2.c3p0.ComboPooledDataSource [ java.beans.IntrospectionException: java.lang.reflect.InvocationTargetException [numThreadsAwaitingCheckoutDefaultUser] ]
org.springframework.transaction.CannotCreateTransactionException: Could not open JDBC Connection for transaction; nested exception is com.mysql.jdbc.exceptions.jdbc4.MySQLNonTransientConnectionException: Data source rejected establishment of connection, message from server: "Too many connections"
Thank you in advance.
Keith

Answer 1

I would agree with axtavt. I was in a similar situation, and there were couple places I was manually opening connections but not closing them (stored procedure calls for iSeries). Please verify if you have that kind of spots.