如何在tomcat中修復java.lang.NoClassDefFoundError

Question

我經常收到以下錯誤消息，由於該錯誤，我懷疑我的應用程序在permGen空間中創建了outofMemory錯誤。

有人可以幫助您解決以下異常。

我正在使用純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

之所以會出現該消息，是因為Web應用程序在關閉后仍在嘗試加載內容。

這樣，它就不會產生“業務影響”（您不必擔心關閉的應用程序中的錯誤），尤其是在關閉整個應用程序服務器的過程中發生錯誤時。

您可能想要弄清楚為什么它不能更徹底地關閉（也許某些后台處理需要在終止webapp時停止）。 如果仍然有東西在運行，則可能會導致其他任何仍在運行的Web應用程序出現問題。

如果您不打算關閉該Web應用程序，則日志中較早的地方可能還有另一個錯誤。