How to use c3p0

himawan · **Joined:** Sat Aug 19, 2006 6:31 pm **Posts:** 139

I'm using Hibernate and EntityManager 3.5.1-Final.

I'm monitoring the number of connections using pgadmin3 and I'm seeing that my application makes more connection than specified in the persistence.xml.

Here's my persistence.xml. And I'm getting and closing EntityManager for every request.

Code:

<persistence xmlns="http://java.sun.com/xml/ns/persistence"
             xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
             xsi:schemaLocation="http://java.sun.com/xml/ns/persistence http://java.sun.com/xml/ns/persistence/persistence_2_0.xsd"
             version="2.0">
   <persistence-unit name="bank" transaction-type="RESOURCE_LOCAL">
      <provider>org.hibernate.ejb.HibernatePersistence</provider>
      <class>com.wms.bank.entities.GameAccount</class>
      <class>com.wms.bank.entities.StationAccount</class>
      <class>com.wms.bank.entities.PlayerAccount</class>
      <properties>
         <property name="hibernate.archive.autodetection" value="none"/>
         <property name="hibernate.hbm2ddl.auto" value="update"/>
         <property name="hibernate.bytecode.use_reflection_optimizer" value="false"/>
         
         <!-- Database specific -->
         <property name="hibernate.connection.driver_class" value="org.postgresql.Driver"/>
         <property name="hibernate.connection.url" value="jdbc:postgresql://127.0.0.1/bank?user=postgres;password=postgres"/>
         <property name="hibernate.dialect" value="org.hibernate.dialect.PostgreSQLDialect"/>
         
         <!-- Connection pool -->
         <property name="hibernate.connection.provider_class" value="org.hibernate.connection.C3P0ConnectionProvider"/>
         <property name="hibernate.c3p0.acquire_increment" value="0"/> 
         <property name="hibernate.c3p0.idle_test_period" value="100"/> <!-- seconds --> 
         <property name="hibernate.c3p0.max_size" value="10"/> 
         <property name="hibernate.c3p0.max_statements" value="0"/> 
         <property name="hibernate.c3p0.min_size" value="5"/> 
         <property name="hibernate.c3p0.timeout" value="100"/> <!-- seconds -->
      </properties>
   </persistence-unit>
</persistence>

Am I missing something?

Thanks

himawan · **Joined:** Sat Aug 19, 2006 6:31 pm **Posts:** 139

I think I figured out my problem. I'm actually running a junit test and apparently new instance of my app gets created for every test case and that created a pool everytime.

I do have another question though. When are connections released back to the pool?

I keep running out of connections (even when I set my max_size to 100) I don't have that many concurrent requests.

Thanks
Budyanto

deanhiller · **Joined:** Thu Sep 16, 2004 4:56 pm **Posts:** 80

freak ;).....heh, it's been a while. Thanks for the post. How's chicago?