如何在tomcat中修复java.lang.NoClassDefFoundError

Question

I'm getting below error message often and due to this error I'm suspecting my application creating outofMemory Error in permGen space.

Can someone help how to fix the below exception.

I'm using pure servlet and tomcat 7.

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.WebappClassLoaderBase.loadClass(WebappClassLoaderBase.java:1745)
    at org.apache.catalina.loader.WebappClassLoaderBase.loadClass(WebappClassLoaderBase.java:1703)
    at com.mchange.v2.resourcepool.BasicResourcePool.checkIdleResources(BasicResourcePool.java:1481)
    at com.mchange.v2.resourcepool.BasicResourcePool.access$2000(BasicResourcePool.java:32)
    at com.mchange.v2.resourcepool.BasicResourcePool$CheckIdleResourcesTask.run(BasicResourcePool.java:1964)
    at java.util.TimerThread.mainLoop(Timer.java:555)
    at java.util.TimerThread.run(Timer.java:505)

Exception in thread "Timer-0" java.lang.NoClassDefFoundError: com/mchange/v2/resourcepool/BasicResourcePool$AsyncTestIdleResourceTask
    at com.mchange.v2.resourcepool.BasicResourcePool.checkIdleResources(BasicResourcePool.java:1481)
    at com.mchange.v2.resourcepool.BasicResourcePool.access$2000(BasicResourcePool.java:32)
    at com.mchange.v2.resourcepool.BasicResourcePool$CheckIdleResourcesTask.run(BasicResourcePool.java:1964)
    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.WebappClassLoaderBase.loadClass(WebappClassLoaderBase.java:1854)
    at org.apache.catalina.loader.WebappClassLoaderBase.loadClass(WebappClassLoaderBase.java:1703)
    ... 5 more

Answer 1

That message just occurs because the web application is still trying to load things after you have shut it down.

As such, it should not have "business impact" (you don't care about errors in an app that you shut down), especially if it happens in the process of shutting down the whole app server.

You may want to figure out why it does not shutdown more cleanly (maybe some background processing that needs to be stopped when the webapp is asked to terminate). If there is stuff still going on in there, that might cause problems for any other web apps still running.

If you did not intend to shut down the webapp, then there is probably another error earlier in the log.