环境
javaweb开发中，Tomcat7，项目运行过程中，出现下面的错误
报错
控制台报错内容如下
信息: 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:1776)
at org.apache.catalina.loader.WebappClassLoaderBase.loadClass(WebappClassLoaderBase.java:1734)
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(Unknown Source)
at java.util.TimerThread.run(Unknown Source)
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(Unknown Source)
at java.util.TimerThread.run(Unknown Source)
Caused by: java.lang.ClassNotFoundException: com.mchange.v2.resourcepool.BasicResourcePool$AsyncTestIdleResourceTask
at org.apache.catalina.loader.WebappClassLoaderBase.loadClass(WebappClassLoaderBase.java:1891)
at org.apache.catalina.loader.WebappClassLoaderBase.loadClass(WebappClassLoaderBase.java:1734)
... 5 more
四月 24, 2020 3:45:01 下午 org.apache.catalina.loader.WebappClassLoaderBase loadClass
信息: Illegal access: this web application instance has been stopped already. Could not load com.mchange.v2.resourcepool.BasicResourcePool$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:1776)
at org.apache.catalina.loader.WebappClassLoaderBase.loadClass(WebappClassLoaderBase.java:1734)
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(Unknown Source)
at java.util.TimerThread.run(Unknown Source)
Exception in thread "Timer-1" 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(Unknown Source)
at java.util.TimerThread.run(Unknown Source)
Caused by: java.lang.ClassNotFoundException: com.mchange.v2.resourcepool.BasicResourcePool$AsyncTestIdleResourceTask
at org.apache.catalina.loader.WebappClassLoaderBase.loadClass(WebappClassLoaderBase.java:1891)
at org.apache.catalina.loader.WebappClassLoaderBase.loadClass(WebappClassLoaderBase.java:1734)
... 5 more
非法访问：这个web应用程序实例已经被停止了。无法加载com.mchange.v2.resourcepool.BasicResourcePool$AsyncTestIdleResourceTask。为了调试目的，抛出了下面的堆栈跟踪，并尝试终止导致非法访问的线程。
原因
在tomcat重启的时候，因为之前的tomcat中的线程还没有完全关闭，新启动tomcat就会报这个异常，不过这个不影响正常使用，只是跳个异常挺烦人的。使用过hibernate, spring或其他大型组件，当一个WEB应用系统中有很多类时，如果开启了Tomcat的reloadable=true,那么每当相关文件改变时， Tomcat会停止web app并释放内存,然后重新加载web app.这实在是个浩大的工程。所以我们总是在想如果能有只重载某几个类的功能，将极大的满足了我们的调试。
解决办法
第一种：新启动tomcat
第二种：修改Tomcat的service.xml的配置
如果重新启动tomcat不能够解决方案。
将tomcat的server.xml中的Context的reloadable设成false。比如:<Context path="/expert" docBase="expert" debug="0" reloadable="false">
在server.xml中并没有找到context的配置信息，所以干脆就把<Context path="/expert" docBase="expert" debug="0" reloadable="false"></Context>加在了server标签内部，
意思就是热部署的意思，修改为false，会失去热部署的优势，而且对于开发也不是很方便，建议不要用这种方式。
<Context path="/expert" docBase="expert" debug="0" reloadable="false"></Context>
加在server.xml里的server标签内就可以