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c3p0 is a simple-to-use Java-based database pooling package.

1 C3P0 manual

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2 How to set up c3p0 with jboss

download c3p0 package from c3p0 website
extract the downloaded binary package and put the c3p0-version.jar into your jboss lib directory ($JBOSS_HOME/server/default/lib)

put the following xml file into your deployment directory ($JBOSS_HOME/server/default/deploy) Note that you need to change JdbcUrl, User, Password into your own configuration


<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE server>
<server>
  <mbean code="com.mchange.v2.c3p0.mbean.C3P0PooledDataSource" name="jboss:service=C3P0PooledDataSource">
  <attribute name="JndiName">java:PooledDS</attribute>
  <attribute name="JdbcUrl">jdbc:postgresql://localhost/c3p0-test</attribute>
  <attribute name="DriverClass">org.postgresql.Driver</attribute>
  <attribute name="User">swaldman</attribute>
  <attribute name="Password">test</attribute>

  <!-- Uncomment and set any of the optional parameters below -->
  <!-- See c3p0's docs for more info. -->
  <!-- <attribute name="AcquireIncrement">3</attribute> -->
  <!-- <attribute name="AcquireRetryAttempts">30</attribute> -->
  <!-- <attribute name="AcquireRetryDelay">1000</attribute> -->
  <!-- <attribute name="AutoCommitOnClose">false</attribute> -->
  <!-- <attribute name="AutomaticTestTable"></attribute> -->
  <!-- <attribute name="BreakAfterAcquireFailure">false</attribute> -->
  <!-- <attribute name="CheckoutTimeout">0</attribute> -->
  <!-- <attribute name="ConnectionTesterClassName">0</attribute> -->
  <!-- <attribute name="Description">A pooled c3p0 DataSource</attribute> -->
  <!-- <attribute name="FactoryClassLocation"></attribute> -->
  <!-- <attribute name="ForceIgnoreUnresolvedTransactions">true</attribute> -->
  <!-- <attribute name="IdleConnectionTestPeriod">-1</attribute> -->
  <!-- <attribute name="InitialPoolSize">3</attribute> -->
  <!-- <attribute name="MaxIdleTime">0</attribute> -->
  <!-- <attribute name="MaxPoolSize">15</attribute> -->
  <!-- <attribute name="MaxStatements">0</attribute> -->
  <!-- <attribute name="MaxStatementsPerConnection">0</attribute> -->
  <!-- <attribute name="MinPoolSize">0</attribute> -->
  <!-- <attribute name="NumHelperThreads">3</attribute> -->
  <!-- <attribute name="PreferredTestQuery"></attribute> -->
  <!-- <attribute name="TestConnectionOnCheckin">false</attribute> -->
  <!-- <attribute name="TestConnectionOnCheckout">false</attribute> -->
  <!-- <attribute name="UsesTraditionalReflectiveProxies">false</attribute> -->
  <depends>jboss:service=Naming</depends>
</mbean>
</server>

you might need to restart jboss if the automatic redeployment doesnot work.

3 "Could not locate driver class with name 'org.postgresql.Driver'", or "Class not found: 'org.postgresql.Driver'"

check to make sure that you have to the postgres driver jar file in your deployment directory ($JBOSS/server/default/deploy) and lib directory ($JBOSS/server/default/lib). In my case, i had to put a copy of the c3p0-version.jar and postgres-jdbc driver jar files in both $JBOSS/server/default/lib and $JBOSS/server/default/deploy to make it work. Also, you could try different jdbc driver versions. In my case, i switched from pg74.216.jdbc3.jar to postgresql-8.0-313.jdbc3.jar.

4 [c3p0] A PooledConnection that has already signalled a Connection error is still in use

You have to use either Transaction.commit even if you are only doing a select. [MS]

Comments

On addition of the c3p0 settings to JBoss as an MBean, does the hibernate config XML have to be modified to point to this new JNDI object --> "java:PooledDS"?

Cheers.

References

[MS] http://www.mikeschubert.com/archives/programming/