在配置文件中的何处放置c3p0属性？

Question

I am using spring/hibernate integrated application. i have configured c3p0 connection pooling. the problem is if i set c3p0 properties in hibernate properties section then those properties are not considered and default configuration is taken. if i set the same properties for combopooled datasource then they are considered. where is the best place to place c3p0 properties.

Below configuration works:

<bean id="dataSource" class="com.mchange.v2.c3p0.ComboPooledDataSource">
        <property name="driverClass" value="${db.driverClassName}" />
        <property name="jdbcUrl" value="${db.url}" />
        <property name="user" value="${db.username}" />
        <property name="password" value="${db.password}" />

        <!-- c3p0  properties -->

        <property name="minPoolSize" value="5" />
        <property name="maxPoolSize" value="20" />
        <property name="maxStatements" value="0" />
        <property name="preferredTestQuery" value="select * from sometable" />
        </bean>

    <bean name="wygSessionFactory" class="org.springframework.orm.hibernate3.LocalSessionFactoryBean">
        <property name="dataSource" ref="dataSource"/>
        <property name="mappingLocations" value="classpath:hibernate/module/*.hbm.xml" />
        <property name="hibernateProperties">
            <props>
                <prop key="hibernate.cache.provider_class">org.hibernate.cache.NoCacheProvider</prop>
                <prop key="hibernate.connection.pool.size">20</prop>
                <prop key="hibernate.dialect">org.hibernate.dialect.OracleDialect</prop>
                 <prop key="hibernate.show_sql">true</prop>
                <prop key="hibernate.format_sql">true</prop>

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

This does not work:

<bean id="dataSource" class="com.mchange.v2.c3p0.ComboPooledDataSource">
        <property name="driverClass" value="${db.driverClassName}" />
        <property name="jdbcUrl" value="${db.url}" />
        <property name="user" value="${db.username}" />
        <property name="password" value="${db.password}" />

                </bean>

    <bean name="wygSessionFactory" class="org.springframework.orm.hibernate3.LocalSessionFactoryBean">
        <property name="dataSource" ref="dataSource"/>
        <property name="mappingLocations" value="classpath:hibernate/module/*.hbm.xml" />
        <property name="hibernateProperties">
            <props>
                <prop key="hibernate.cache.provider_class">org.hibernate.cache.NoCacheProvider</prop>
                <prop key="hibernate.connection.pool.size">20</prop>
                <prop key="hibernate.dialect">org.hibernate.dialect.OracleDialect</prop>
                 <prop key="hibernate.show_sql">true</prop>
                <prop key="hibernate.format_sql">true</prop>
<!-- c3p0  properties -->
                <prop key="hibernate.c3p0.min_size">5</prop>
                <prop key="hibernate.c3p0.max_size">20</prop>
                <prop key="hibernate.c3p0.timeout">300</prop>
                <prop key="hibernate.c3p0.max_statements">0</prop>
                <prop key="hibernate.c3p0.preferredTestQuery">select * from sometable</prop>

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

Answer 1

I was getting the same problem and it took time to figure out the solution.

I use Hibernate 4.0.1 and mysql 5.1(no spring framework) and I was facing the issue. First make sure that you configured the c3p0 jars properly which are essential.

I used these properties in hibernate.cfg.xml

<property name="hibernate.c3p0.validate">true</property>
<property name="hibernate.connection.provider_class">org.hibernate.service.jdbc.connections.internal.C3P0ConnectionProvider</property>
<property name="hibernate.c3p0.min_size">5</property>
<property name="hibernate.c3p0.max_size">20</property>
<property name="hibernate.c3p0.max_statements">50</property>
<property name="hibernate.c3p0.preferredTestQuery">SELECT 1;</property>
<property name="hibernate.c3p0.testConnectionOnCheckout">true</property>
<property name="hibernate.c3p0.idle_test_period">10</property>
<property name="hibernate.c3p0.acquireRetryAttempts">5</property>
<property name="hibernate.c3p0.acquireRetryDelay">200</property>
<property name="hibernate.c3p0.timeout">40</property>

But it's of no use 'cause C3p0 was still taking the default properties not the properties which I set in hibernate.cfg.xml, You can check it in logs. So, I searched many websites for right solution and finally I came up with this. remove the C3p0 properties in cfg.xml and create c3p0-config.xml in the root path(along with cfg.xml) and set properties as follows.

<c3p0-config>
<default-config> 
<property name="automaticTestTable">con_test</property>
<property name="checkoutTimeout">40</property> 
<property name="idleConnectionTestPeriod">10</property> 
<property name="initialPoolSize">10</property>
<property name="maxPoolSize">20</property> 
<property name="minPoolSize">5</property> 
<property name="maxStatements">50</property>
<property name="preferredTestQuery">SELECT 1;</property>
<property name="acquireRetryAttempts">5</property>
<property name="acquireRetryDelay">200</property>
<property name="maxIdleTime">30</property>
</default-config>
</c3p0-config>

but if you run, ORM takes the jdbc connection but not C3p0 connection pool 'cause we should add these properties in hibernate.cfg.xml

<property name="hibernate.c3p0.validate">true</property>

<property name="hibernate.connection.provider_class">org.hibernate.service.jdbc.connections.internal.C3P0ConnectionProvider</property>

now everything works fine(At least it worked fine for me) and the issue is solved.

check the following for references.

http://www.mchange.com/projects/c3p0/index.html#configuring_connection_testing

https://community.jboss.org/wiki/HowToConfigureTheC3P0ConnectionPool

I hope this solves your problem.