关闭Tomcat(7.0)老出现这样的严重提示是什么原因？

SSH项目，用DBCP连接数据库，下面是提示信息

2011-10-14 15:19:39 org.apache.catalina.loader.WebappClassLoader clearReferencesJdbc
严重: The web application [/marketservice] registered the JDBC driver [oracle.jdbc.driver.OracleDriver] but failed to unregister it when the web application was stopped. To prevent a memory leak, the JDBC Driver has been forcibly unregistered.
2011-10-14 15:19:39 org.apache.catalina.loader.WebappClassLoader clearReferencesThreads
严重: The web application [/marketservice] appears to have started a thread named [FileWatchdog] but has failed to stop it. This is very likely to create a memory leak.
2011-10-14 15:19:39 org.apache.catalina.loader.WebappClassLoader clearReferencesThreads
严重: The web application [/marketservice] appears to have started a thread named [Timer-0] but has failed to stop it. This is very likely to create a memory leak.
2011-10-14 15:19:39 org.apache.catalina.loader.WebappClassLoader checkThreadLocalMapForLeaks
严重: The web application [/marketservice] created a ThreadLocal with key of type com.opensymphony.xwork2.inject.ContainerImpl$10 and a value of type java.lang.Object[] but failed to remove it when the web application was stopped. Threads are going to be renewed over time to try and avoid a probable memory leak.
2011-10-14 15:19:39 org.apache.coyote.AbstractProtocolHandler stop
信息: Stopping ProtocolHandler ["http-bio-8080"]
2011-10-14 15:19:39 org.apache.coyote.AbstractProtocolHandler stop
信息: Stopping ProtocolHandler ["ajp-bio-8009"]