c3p0 - hibernate - mysql

Question

• hibernate 3.6.8 final

• c3p0 jar that came with hibernate 3.6.8 package -> c3p0-0.9.1.jar

  1 15 40 0 5 2

The app seems to be working fine, however I get massive log calls with the following stacktrace:

org.apache.catalina.loader.WebappClassLoader loadClass
INFO: Illegal access: this web application instance has been stopped already.  Could not load com.mysql.jdbc.exceptions.jdbc4.MySQLNonTransientConnectionException.  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:1566)
    at org.apache.catalina.loader.WebappClassLoader.loadClass(WebappClassLoader.java:1526)
    at java.lang.Class.forName0(Native Method)
    at java.lang.Class.forName(Class.java:169)
    at com.mysql.jdbc.Util.getInstance(Util.java:386)
    at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:1013)
    at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:987)
    at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:982)
    at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:927)
    at com.mysql.jdbc.ConnectionImpl.connectOneTryOnly(ConnectionImpl.java:2411)
    at com.mysql.jdbc.ConnectionImpl.createNewIO(ConnectionImpl.java:2153)
    at com.mysql.jdbc.ConnectionImpl.<init>(ConnectionImpl.java:792)
    at com.mysql.jdbc.JDBC4Connection.<init>(JDBC4Connection.java:47)
    at sun.reflect.GeneratedConstructorAccessor38.newInstance(Unknown Source)
    at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:27)
    at java.lang.reflect.Constructor.newInstance(Constructor.java:513)
    at com.mysql.jdbc.Util.handleNewInstance(Util.java:411)
    at com.mysql.jdbc.ConnectionImpl.getInstance(ConnectionImpl.java:381)
    at com.mysql.jdbc.NonRegisteringDriver.connect(NonRegisteringDriver.java:305)
    at com.mchange.v2.c3p0.DriverManagerDataSource.getConnection(DriverManagerDataSource.java:134)
    at com.mchange.v2.c3p0.WrapperConnectionPoolDataSource.getPooledConnection(WrapperConnectionPoolDataSource.java:182)
    at com.mchange.v2.c3p0.WrapperConnectionPoolDataSource.getPooledConnection(WrapperConnectionPoolDataSource.java:171)
    at com.mchange.v2.c3p0.impl.C3P0PooledConnectionPool$1PooledConnectionResourcePoolManager.acquireResource(C3P0PooledConnectionPool.java:152)
    at com.mchange.v2.resourcepool.BasicResourcePool.doAcquire(BasicResourcePool.java:1074)
    at com.mchange.v2.resourcepool.BasicResourcePool.doAcquireAndDecrementPendingAcquiresWithinLockOnSuccess(BasicResourcePool.java:1061)
    at com.mchange.v2.resourcepool.BasicResourcePool.access$800(BasicResourcePool.java:32)
    at com.mchange.v2.resourcepool.BasicResourcePool$ScatteredAcquireTask.run(BasicResourcePool.java:1796)
    at com.mchange.v2.async.ThreadPoolAsynchronousRunner$PoolThread.run(ThreadPoolAsynchronousRunner.java:620)

Any information on how to remove that INFO log would be very much helpful thanks!

UPDATE: Is this a critical error? Or can should I just ignore it?

Answer 1

After a search on the web regarding this issue, I found some similar issues reported by several people. All of them point to a common problem: Threads. Basically, if you start new threads in your application (either in your code or by using a third party tool like Quartz, you have to make sure that all of the threads are stopped appropriately when the application is undeployed from the server. Here are some quotes from the searches:

Mikolaj Rydzewski wrote:

It looks like after webapp's instance has been undeployed, background quartz thread wants to do something and then exception occurs.

Another (and better explanation) on jspwiki.org:

It is possible that this is caused by Tomcat unsuccessfully reloading the web application. The app is unloaded, but all threads don't get shut down properly. As a result, when the threads try to run, they get clobbered by the fact that Tomcat has shut down its classloader, and an error is logged.

So, in order to solve this issue you have to make sure all threads started by your application will be stopped at application undeployment (or redeployment, it's the same). You can do this by registering a ServletContextListener to your application server and stopping your threads inside contextDestroyed(ServletContextEvent) method.

Answer 2

OK I switched to boneCP, c3p0 does not really seem to work for java6!!!

Answer 3

If you are using log4j, change your logging settings to something like this (the word ERROR replace INFO) :

log4j.rootLogger=ERROR, file, stdout
log4j.logger.org.hibernate=ERROR

They are located in the the log4j.properties file in yr project.