By default, Hibernate uses JDBC connections in order to interact with a database. Creating these connections is expensive—probably the most expensive single operation Hibernate will execute in a typical-use case. Since JDBC connection management is so expensive that possibly you will advise to use a pool of connections, which can open connections ahead of time (and close them only when needed, as opposed to “when they’re no longer used”).
C3P0 is an example of an external connection pool. In this tutorial, we will learn to use it with hibernate.
Table of Contents 1) Maven dependencies 2) Configure C3P0 Connection Pool with Hibernate 3) Test connection pooling in runtime
1) Maven dependencies
To configure c3p0 with hibernate, we need to add c3p0 and Hibernate’s c3p0 connection provider as dependencies in the pom.xml. Please note that the version of the hibernate-c3p0 dependency should match the Hibernate’s compatible version.
Below configuration uses the latest versions of both i.e. hibernate as well as c3p0.
<dependency>
<groupId>org.hibernate</groupId>
<artifactId>hibernate-c3p0</artifactId>
<version>4.3.6.Final</version>
</dependency>
<dependency>
<groupId>c3p0</groupId>
<artifactId>c3p0</artifactId>
<version>0.9.1.2</version>
</dependency>
2) Configure C3P0 Connection Pool with Hibernate
The best part is that the configuration of C3P0 with hibernate is really very easy. Just add any c3p0 property inside your hibernate.cfg.xml file and that’s it. e.g. add the following entry in hibernate.cfg.xml.
<property name="hibernate.c3p0.min_size">10</property>
Congratulations !! Connection pooling with C3P0 is now configured with your application’s hibernate layer. You are good to start testing the things. Really easy, Isn’t it?
A rather detailed configuration can be setup using following properties in hibernate.cfg.xml.
<property name="hibernate.c3p0.min_size">10</property> <property name="hibernate.c3p0.max_size">20</property> <property name="hibernate.c3p0.acquire_increment">1</property> <property name="hibernate.c3p0.idle_test_period">3000</property> <property name="hibernate.c3p0.max_statements">50</property> <property name="hibernate.c3p0.timeout">1800</property>
You can find detailed information about about above configuration switches in official documentation.
3) Test connection pooling in runtime
Without C3P0 Connection Pool Configuration
Without C3P0 configured, if you see the debug logs of hibernate, you will see something like this:
DEBUG Configuration:1841 - Preparing to build session factory with filters : {}
WARN DriverManagerConnectionProviderImpl:93 - HHH000402: Using Hibernate built-in connection pool (not for production use!)
INFO DriverManagerConnectionProviderImpl:166 - HHH000401: using driver [org.hsqldb.jdbcDriver] at URL [jdbc:hsqldb:mem:howtodoinjava]
INFO DriverManagerConnectionProviderImpl:172 - HHH000046: Connection properties: {user=sa, password=}
INFO DriverManagerConnectionProviderImpl:180 - HHH000006: Autocommit mode: false
INFO DriverManagerConnectionProviderImpl:102 - HHH000115: Hibernate connection pool size: 20 (min=1)
DEBUG DriverManagerConnectionProviderImpl:104 - Initializing Connection pool with 1 Connections
...
...
...
EBUG JdbcTransaction:113 - committed JDBC Connection
DEBUG SessionFactoryImpl:1339 - HHH000031: Closing
DEBUG AbstractServiceRegistryImpl:406 - Implicitly destroying ServiceRegistry on de-registration of all child ServiceRegistries
INFO DriverManagerConnectionProviderImpl:281 - HHH000030: Cleaning up connection pool [jdbc:hsqldb:mem:howtodoinjava]
Using C3P0 Connection Pool Configuration
After configuring C3P0 Connection Pool, you will be able to see in the logs that connections are now acquired from C3P0 Connection Pool itself.
DEBUG Configuration:1841 - Preparing to build session factory with filters : {}
INFO C3P0ConnectionProvider:133 - HHH010002: C3P0 using driver: org.hsqldb.jdbcDriver at URL: jdbc:hsqldb:mem:howtodoinjava
INFO C3P0ConnectionProvider:134 - HHH000046: Connection properties: {user=sa, password=****}
INFO C3P0ConnectionProvider:137 - HHH000006: Autocommit mode: false
INFO MLog:92 - MLog clients using log4j logging.
INFO C3P0Registry:216 - Initializing c3p0-0.9.2.1 [built 20-March-2013 10:47:27 +0000; debug? true; trace: 10]
DEBUG DynamicPooledDataSourceManagerMBean:258 - MBean: com.mchange.v2.c3p0:type=PooledDataSource,identityToken=19tu9of94ho8s13xij3fm|34e475e1,name=19tu9of94ho8s13xij3fm|34e475e1 registered.
DEBUG DynamicPooledDataSourceManagerMBean:253 - MBean: com.mchange.v2.c3p0:type=PooledDataSource,identityToken=19tu9of94ho8s13xij3fm|34e475e1,name=19tu9of94ho8s13xij3fm|34e475e1 unregistered, in order to be reregistered after update.
DEBUG DynamicPooledDataSourceManagerMBean:258 - MBean: com.mchange.v2.c3p0:type=PooledDataSource,identityToken=19tu9of94ho8s13xij3fm|34e475e1,name=19tu9of94ho8s13xij3fm|34e475e1 registered.
INFO AbstractPoolBackedDataSource:522 - Initializing c3p0 pool... com.mchange.v2.c3p0.PoolBackedDataSource@d29bbf50 [ connectionPoolDataSource -> com.mchange.v2.c3p0.WrapperConnectionPoolDataSource@a9bbd924 [ ... ]
...
...
...
DEBUG ActiveManagementCoordinator:97 - C3P0Registry mbean unregistered.
DEBUG BasicResourcePool:1022 - Preparing to destroy resource: com.mchange.v2.c3p0.impl.NewPooledConnection@1d1fcfbb
DEBUG C3P0PooledConnectionPool:616 - Preparing to destroy PooledConnection: com.mchange.v2.c3p0.impl.NewPooledConnection@1d1fcfbb
DEBUG AbstractPoolBackedDataSource:477 - com.mchange.v2.c3p0.PoolBackedDataSource@34e475e1 has been closed.
java.lang.Exception: DEBUG STACK TRACE for PoolBackedDataSource.close().
at com.mchange.v2.c3p0.impl.AbstractPoolBackedDataSource.close(AbstractPoolBackedDataSource.java:477)
at com.mchange.v2.c3p0.impl.AbstractPoolBackedDataSource.close(AbstractPoolBackedDataSource.java:489)
at com.mchange.v2.c3p0.DataSources.destroy(DataSources.java:372)
at com.mchange.v2.c3p0.DataSources.destroy(DataSources.java:348)
at org.hibernate.c3p0.internal.C3P0ConnectionProvider.stop(C3P0ConnectionProvider.java:258)
at org.hibernate.service.internal.AbstractServiceRegistryImpl.stopService(AbstractServiceRegistryImpl.java:377)
at org.hibernate.service.internal.AbstractServiceRegistryImpl.destroy(AbstractServiceRegistryImpl.java:361)
at org.hibernate.service.internal.AbstractServiceRegistryImpl.deRegisterChild(AbstractServiceRegistryImpl.java:410)
at org.hibernate.service.internal.AbstractServiceRegistryImpl.destroy(AbstractServiceRegistryImpl.java:368)
at org.hibernate.internal.SessionFactoryImpl.close(SessionFactoryImpl.java:1377)
at com.howtodoinjava.demo.util.HibernateUtil.shutdown(HibernateUtil.java:39)
at com.howtodoinjava.test.TestHibernate.main(TestHibernate.java:22)
That’s all for this easy but useful tutorial about configuring C3P0 Connection Pool with hibernate.
Happy Learning !!
Reference: http://www.mchange.com/projects/c3p0/#configuration
partha
sir if am creating a connection pool in tomcat with c3p0 then how to use it in hibernate
Lokesh
As mentioned in post, all you need to do is define any property in hibernate config file starting with “hibernate.c3p0.”. Then hibernate will take care of everything in backend.