My Spring application leaks database connections whereas I use the default Roo configuration - spring

Question

I am encountering an serious issue with my application. It leaks database connections whereas I use the default Spring Roo datasource configuration as follows:
<bean class="org.apache.commons.dbcp.BasicDataSource" destroy-method="close" id="dataSource">
<property name="driverClassName" value="${database.driverClassName}" />
<property name="url" value="${database.url}" />
<property name="username" value="${database.username}" />
<property name="password" value="${database.password}" />
<property name="testOnBorrow" value="true" />
<property name="testOnReturn" value="true" />
<property name="testWhileIdle" value="true" />
<property name="timeBetweenEvictionRunsMillis" value="1800000" />
<property name="numTestsPerEvictionRun" value="3" />
<property name="minEvictableIdleTimeMillis" value="1800000" />
<property name="validationQuery" value="SELECT 1" />
<property name="maxActive" value="2"/>
<property name="logAbandoned" value="true"/>
<property name="removeAbandoned" value="true"/>
</bean>
Here is the controller method that causes the leak:
#RequestMapping(value = "getMessages", method = RequestMethod.GET, produces = "application/json")
#ResponseBody
public DeferredResult<List<Message>> getMessages(#RequestParam final Long senderId) {
// TODO: check that recipientId was not changed by malicious user!!
final Long recipientId = memberService.retrieveCurrentMember().getId();
final String messageRequestKey = new StringBuilder().append(senderId).append(":").append(recipientId).toString();
final DeferredResult<List<Message>> deferredResult = new DeferredResult<List<Message>>(null, Collections.emptyList());
messageRequests.put(messageRequestKey, deferredResult);
deferredResult.onCompletion(new Runnable() {
#Override
public void run() {
messageRequests.remove(messageRequestKey);
}
});
List<Message> unReadMessages = messageService.findUnreadMessages(senderId, recipientId);
if (!unReadMessages.isEmpty()) {
deferredResult.setResult(unReadMessages);
}
return deferredResult;
}
It appears that connections are not returned to the pool by the above method (which is polled continuously by ajax).
Can anyone please help?
EDIT:
Hibernate config:
<persistence-unit name="persistenceUnit" transaction-type="RESOURCE_LOCAL">
<provider>org.hibernate.ejb.HibernatePersistence</provider>
<properties>
<property name="hibernate.dialect" value="org.hibernate.dialect.MySQL5InnoDBDialect"/>
<!-- value="create" to build a new database on each run; value="update" to modify an existing database; value="create-drop" means the same as "create" but also drops tables when Hibernate closes; value="validate" makes no changes to the database -->
<property name="hibernate.hbm2ddl.auto" value="update"/>
<property name="hibernate.ejb.naming_strategy" value="org.hibernate.cfg.ImprovedNamingStrategy"/>
<property name="hibernate.connection.charSet" value="UTF-8"/>
<property name="hibernate.show_sql" value="true"/>
<property name="hibernate.format_sql" value="true"/>
<property name="hibernate.use_sql_comments" value="true"/>
<property name="hibernate.connection.release_mode" value="after_transaction"/>
</properties>
</persistence-unit>
Hibernate version:
<dependency>
<groupId>org.hibernate</groupId>
<artifactId>hibernate-core</artifactId>
<version>4.1.8.Final</version>
</dependency>
<dependency>
<groupId>org.hibernate</groupId>
<artifactId>hibernate-entitymanager</artifactId>
<version>4.1.8.Final</version>
<exclusions>
<exclusion>
<groupId>cglib</groupId>
<artifactId>cglib</artifactId>
</exclusion>
<exclusion>
<groupId>dom4j</groupId>
<artifactId>dom4j</artifactId>
</exclusion>
</exclusions>
</dependency>
<dependency>
<groupId>org.hibernate.javax.persistence</groupId>
<artifactId>hibernate-jpa-2.0-api</artifactId>
<version>1.0.1.Final</version>
</dependency>

Answer 1

I'm not sure if you are using hibernate? If so take a look at the setting hibernate.connection.release_mode . We had this issue and putting it to after_transaction solved all our connection issues.
EDIT
Our config:
<beans:bean id="entityManagerFactory"
class="org.springframework.orm.jpa.LocalContainerEntityManagerFactoryBean">
<beans:property name="dataSource" ref="mvcDatasource" />
<beans:property name="persistenceUnitName" value="mvcPersistenceUnit" />
<beans:property name="persistenceProvider">
<beans:bean class="org.hibernate.ejb.HibernatePersistence" />
</beans:property>
<!-- Fix Hibernate not properly connected with spring -->
<beans:property name="jpaVendorAdapter">
<beans:bean class="org.springframework.orm.jpa.vendor.HibernateJpaVendorAdapter" />
</beans:property>
<beans:property name="jpaPropertyMap">
<beans:map>
<!-- Connection release fix -->
<beans:entry key="hibernate.connection.release_mode" value="after_transaction" />
<beans:entry key="hibernate.dialect" value="${hibernate.dialect}" />
...
</beans:map>
</beans:property>
</beans:bean>