Unable to release JDBC Connection

Question

I'm new to JPA & Hibernate, I'm performing reset password action. In that case, the entity object (User) is getting updated after that I'm trying to log-in but unfortunately, the server is hung and I was getting the below exception.

javax.persistence.PersistenceException: org.hibernate.exception.JDBCConnectionException: Unable to release JDBC Connection

Below is our persistence file configuration

<properties>

  <!-- Configuring JDBC properties -->
  <property name="javax.persistence.jdbc.url" value="jdbc:mysql://127.0.0.1:3306/dbname?autoReconnect=true&amp;useUnicode=true" />
  <property name="javax.persistence.jdbc.driver" value="com.mysql.cj.jdbc.Driver" />
  <property name="javax.persistence.jdbc.user" value="username" />
  <property name="javax.persistence.jdbc.password" value="password" />
  <property name="hibernate.jdbc.batch_size" value="80000" />
  <property name="hibernate.show_sql" value="false" />
  <property name="hibernate.format_sql" value="false" />
  <property name="hibernate.use_sql_comments" value="false" />
  <property name="hibernate.hbm2ddl.auto" value="none" />
  <property name="hibernate.dialect" value="org.hibernate.dialect.MySQL5InnoDBDialect" />
  <property name="hibernate.connection.charSet" value="UTF-8" />
  <property name="hibernate.max_fetch_depth" value="2" />

  <!-- Configuring Connection Pool -->
  <property name="hibernate.c3p0.min_size" value="10" />      
  <property name="hibernate.c3p0.max_size" value="250" />
  <property name="hibernate.c3p0.acquire_increment" value="10"/>
  <property name="hibernate.c3p0.timeout" value="500" />
  <property name="hibernate.c3p0.max_statements" value="50" />
  <property name="hibernate.c3p0.idle_test_period" value="2000" />

  <!-- Newly added -->
  <property name="hibernate.c3p0.maxConnectionAge" value="300"/>
  <property name="hibernate.c3p0.maxIdleTimeExcessConnections" value="300"/>
  <property name="hibernate.c3p0.testConnectionOnCheckin" value="true"/>
  <property name="hibernate.c3p0.preferredTestQuery" value="select 1"/>
  <property name="hibernate.c3p0.validate" value="false"/>
  <property name="hibernate.c3p0.testConnectionOnCheckout" value="false" />
</properties>

Can anyone help me what I made mistake? anything I missed in the configuration file?

Old Ben Murphy · Answer 1 · 2016-12-12T20:19:58.433

This is my set up and works perfect with hibernate 5.2.4 and spring mvc 4.3.4 and Maven 3.3.9

<!-- Set Up data base DataSource and the connection pool -->
<bean id="dataSource" class="com.mchange.v2.c3p0.ComboPooledDataSource"
      destroy-method="close">
    <property name="driverClass" value="com.mysql.jdbc.Driver" />
    <property name="jdbcUrl" value="jdbc:mysql://localhost:3306/mySchemaName?useSSL=false" />
    <property name="user" value="root" />
    <property name="password" value="**********" /> 

    <!-- the connection pool properties for C3P0 -->
    <property name="minPoolSize" value="5" />
    <property name="maxPoolSize" value="20" />
    <property name="maxIdleTime" value="30000" />
</bean>  

<!-- Setu session factory for Hibernate -->
<bean id="sessionFactory"
    class="org.springframework.orm.hibernate5.LocalSessionFactoryBean">
    <property name="dataSource" ref="dataSource" />
    <property name="packagesToScan" value="com.package.whatever" />
    <property name="hibernateProperties">
       <props>
          <prop key="hibernate.dialect">org.hibernate.dialect.MySQLDialect</prop>
          <prop key="hibernate.show_sql">true</prop>
       </props>
    </property>

<!--  Setup Hibernate transaction manager -->
<bean id="myTransactionManager"
        class="org.springframework.orm.hibernate5.HibernateTransactionManager">
    <property name="sessionFactory" ref="sessionFactory"/>
</bean>

Tip: If you are using glassfish server 4.1.1 you have to find glasfish/domains/domain1/modules and replace jboss-logger with the newest jboss-logger 3.3.0

thank you. I found the issue which was the Entity (User) using too many EAGER fetch type so it takes too much time to execute the query Let's say I was using 18 EAGER Fetch type to make Join other entity in the User Entity. We used detach the updated entity from the entity manager. Is it correct way? or else we want to do some optimization? — Sathish Thangathurai, Dec 13 '16 at 16:03
check this http://stackoverflow.com/questions/2990799/difference-between-fetchtype-lazy-and-eager-in-java-persistence-api it may help but if you found a way that works i guess its good ! — Old Ben Murphy, Dec 14 '16 at 14:29
OK got it but in my case we want Eager while fetching the list in the same time we need to avoid Eager while updating how can I achieve this?. Thanks for your information. — Sathish Thangathurai, Dec 15 '16 at 13:14

Unable to release JDBC Connection

1 Answers1