如何在tomcat中修复java.lang.NoClassDefFoundError

Question

我经常收到以下错误消息，由于该错误，我怀疑我的应用程序在permGen空间中创建了outofMemory错误。

有人可以帮助您解决以下异常。

我正在使用纯servlet和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

之所以会出现该消息，是因为Web应用程序在关闭后仍在尝试加载内容。

这样，它就不会产生“业务影响”（您不必担心关闭的应用程序中的错误），尤其是在关闭整个应用程序服务器的过程中发生错误时。

您可能想要弄清楚为什么它不能更彻底地关闭（也许某些后台处理需要在终止webapp时停止）。 如果仍然有东西在运行，则可能会导致其他任何仍在运行的Web应用程序出现问题。

如果您不打算关闭该Web应用程序，则日志中较早的地方可能还有另一个错误。