Issues with Hibernate and C3p0 pool

Question

I'm testing web application with hibernate 4.3.0 and c3p0 pool and sometimes after reloading context I get this error:

 INFO: Reloading Context with name [/AppName] is completed
    янв 07, 2015 12:07:14 AM org.apache.catalina.loader.WebappClassLoader loadClass
    INFO: Illegal access: this web application instance has been stopped already.  Could not load com.mchange.v2.resourcepool.BasicResourcePool$AsyncTestIdleResourceTask.  The eventual following stack trace is caused by an error thrown for debugging purposes as well as to attempt to terminate the thread which caused the illegal access, and has no functional impact.
    java.lang.IllegalStateException
        at org.apache.catalina.loader.WebappClassLoader.loadClass(WebappClassLoader.java:1612)
        at org.apache.catalina.loader.WebappClassLoader.loadClass(WebappClassLoader.java:1571)
        at com.mchange.v2.resourcepool.BasicResourcePool.checkIdleResources(BasicResourcePool.java:1584)
        at com.mchange.v2.resourcepool.BasicResourcePool.access$2000(BasicResourcePool.java:44)
        at com.mchange.v2.resourcepool.BasicResourcePool$CheckIdleResourcesTask.run(BasicResourcePool.java:2116)
        at java.util.TimerThread.mainLoop(Timer.java:555)
        at java.util.TimerThread.run(Timer.java:505)

Exception in thread "C3P0PooledConnectionPoolManager[identityToken->1hge136961hmilhm17ylc97|17d425e]-AdminTaskTimer" java.lang.NoClassDefFoundError: com/mchange/v2/resourcepool/BasicResourcePool$AsyncTestIdleResourceTask
    at com.mchange.v2.resourcepool.BasicResourcePool.checkIdleResources(BasicResourcePool.java:1584)
    at com.mchange.v2.resourcepool.BasicResourcePool.access$2000(BasicResourcePool.java:44)
    at com.mchange.v2.resourcepool.BasicResourcePool$CheckIdleResourcesTask.run(BasicResourcePool.java:2116)
    at java.util.TimerThread.mainLoop(Timer.java:555)
    at java.util.TimerThread.run(Timer.java:505)
Caused by: java.lang.ClassNotFoundException: com.mchange.v2.resourcepool.BasicResourcePool$AsyncTestIdleResourceTask
    at org.apache.catalina.loader.WebappClassLoader.loadClass(WebappClassLoader.java:1720)
    at org.apache.catalina.loader.WebappClassLoader.loadClass(WebappClassLoader.java:1571)
    ... 5 more

dependencies - maybe hibernate-c3p0 dependecie is enougth?

<dependency>
    <groupId>com.mchange</groupId>
    <artifactId>c3p0</artifactId>
    <version>0.9.2.1</version>
</dependency>

<dependency>
    <groupId>org.hibernate</groupId>
    <artifactId>hibernate-c3p0</artifactId>
    <version>4.3.0.Final</version>
</dependency>

hibernate settings

<property name="connection.provider_class">org.hibernate.connection.C3P0ConnectionProvider</property>

        <property name="hibernate.c3p0.min_size">5</property>
        <property name="hibernate.c3p0.max_size">20</property>
        <property name="hibernate.c3p0.timeout">3000</property>
        <property name="hibernate.c3p0.max_statements">50</property>
        <property name="hibernate.c3p0.idle_test_period">300</property>

What is the reason for that error and hot to fix it? All dependecies related to hibernate-c3p0 are in the classpath.

Answer 1

Please refer to the links I added as comments. During re-deployment classes are unloaded, if you fail to close Hibernate's sessionFactory then you get these ClassNotFound errors. One of the answer suggest that you can add a custom ServletContextListener to handle the contextDestroyed event.