java.lang.IllegalStateException项目运行一会儿后，自动报的错误

Question

java.lang.IllegalStateException: Illegal access: this web application instance has been stopped already. Could not load [com.mchange.v2.resourcepool.BasicResourcePool$1DestroyResourceTask]. The following stack trace is thrown for debugging purposes as well as to attempt to terminate the thread which caused the illegal access.
at org.apache.catalina.loader.WebappClassLoaderBase.checkStateForResourceLoading(WebappClassLoaderBase.java:1305)
at org.apache.catalina.loader.WebappClassLoaderBase.checkStateForClassLoading(WebappClassLoaderBase.java:1293)
at org.apache.catalina.loader.WebappClassLoaderBase.loadClass(WebappClassLoaderBase.java:1158)
at org.apache.catalina.loader.WebappClassLoaderBase.loadClass(WebappClassLoaderBase.java:1119)
at com.mchange.v2.resourcepool.BasicResourcePool.destroyResource(BasicResourcePool.java:1040)
at com.mchange.v2.resourcepool.BasicResourcePool.removeResource(BasicResourcePool.java:1507)
at com.mchange.v2.resourcepool.BasicResourcePool.removeResource(BasicResourcePool.java:1477)
at com.mchange.v2.resourcepool.BasicResourcePool.cullExpired(BasicResourcePool.java:1565)
at com.mchange.v2.resourcepool.BasicResourcePool.access$1900(BasicResourcePool.java:44)
at com.mchange.v2.resourcepool.BasicResourcePool$CullTask.run(BasicResourcePool.java:2089)
at java.util.TimerThread.mainLoop(Timer.java:555)
at java.util.TimerThread.run(Timer.java:505)
Exception in thread "C3P0PooledConnectionPoolManager[identityToken->1hge2h29m1zvigj1c8yih|3bfe9985]-AdminTaskTimer" java.lang.NoClassDefFoundError: com/mchange/v2/resourcepool/BasicResourcePool$1DestroyResourceTask
at com.mchange.v2.resourcepool.BasicResourcePool.destroyResource(BasicResourcePool.java:1040)
at com.mchange.v2.resourcepool.BasicResourcePool.removeResource(BasicResourcePool.java:1507)
at com.mchange.v2.resourcepool.BasicResourcePool.removeResource(BasicResourcePool.java:1477)
at com.mchange.v2.resourcepool.BasicResourcePool.cullExpired(BasicResourcePool.java:1565)
at com.mchange.v2.resourcepool.BasicResourcePool.access$1900(BasicResourcePool.java:44)
at com.mchange.v2.resourcepool.BasicResourcePool$CullTask.run(BasicResourcePool.java:2089)
at java.util.TimerThread.mainLoop(Timer.java:555)
at java.util.TimerThread.run(Timer.java:505)
Caused by: java.lang.ClassNotFoundException: Illegal access: this web application instance has been stopped already. Could not load [com.mchange.v2.resourcepool.BasicResourcePool$1DestroyResourceTask]. The following stack trace is thrown for debugging purposes as well as to attempt to terminate the thread which caused the illegal access.
at org.apache.catalina.loader.WebappClassLoaderBase.checkStateForClassLoading(WebappClassLoaderBase.java:1295)
at org.apache.catalina.loader.WebappClassLoaderBase.loadClass(WebappClassLoaderBase.java:1158)
at org.apache.catalina.loader.WebappClassLoaderBase.loadClass(WebappClassLoaderBase.java:1119)
... 8 more
Caused by: java.lang.IllegalStateException: Illegal access: this web application instance has been stopped already. Could not load [com.mchange.v2.resourcepool.BasicResourcePool$1DestroyResourceTask]. The following stack trace is thrown for debugging purposes as well as to attempt to terminate the thread which caused the illegal access.
at org.apache.catalina.loader.WebappClassLoaderBase.checkStateForResourceLoading(WebappClassLoaderBase.java:1305)
at org.apache.catalina.loader.WebappClassLoaderBase.checkStateForClassLoading(WebappClassLoaderBase.java:1293)
... 10 more
这个问题，时不时的发生。也不知道是什么原因
自从换了C3P0连接池之后，就会发生这个问题
org.hibernate.connection.C3P0ConnectionProvider
100
5
120
1800
<!-- Test -->
<!-- JDBC的标准参数，用以控制数据源内加载的PreparedStatements数量。但由于预缓存的statements属于单个connection而不是整个连接池。所以设置这个参数需要考虑到多方面的因素。如果maxStatements与maxStatementsPerConnection均为0，则缓存被关闭。 -->
0
<!-- 每隔多少秒检查连接池中的空闲连接 -->
1800
<!-- 当c3p0连接池枯竭时，一次获得多少连接的数量 -->
3
<!-- 因性能消耗大请只在需要的时候使用它。如果设为true那么在每个connection提交的时候都将校验其有效性。建议使用idleConnectionTestPeriod或automaticTestTable等方法来提升连接测试的性能。Default: false -->
false

<!-- 每次都验证连接是否可用 -->
false

org.hibernate.dialect.SQLServerDialect

我是初学者，也不知道哪里配的有问题
这也是，我第一次在CSDN上提问。望各位前辈，指点一二

Answer 1

出现这个问题之前你是不是restart过tomcat。
如果是的话，会有这个问题，C3P0会有三个守护线程，在tomcat重启的时候，这三个守护线程不会被Kill掉.
在这种情况下，tomcat的restart首先会unload装载的class，然后再启动这时会加载新的class，但是c3p0的守护线程没有关闭，
它们还是会去读原有的class，这样的情况下会出现你贴出来的 java.lang.NoClassDefFoundError: com/mchange/v2/resourcepool/BasicResourcePool$1DestroyResourceTask

目前没有好的方法去解决这一块，要么你不用c3p0用阿里开源的Druid，要么用一个转换方法，用ServletContextListener去监听容器destory事件，然后在监听器里面去把Hibernate的sessionFactory显示destory掉。

https://forums.hibernate.org/viewtopic.php?t=924835&view=next&sid=abc532479937768dd0fd58e82a1f465f