Originally reported at the user mailing list, see:
When the web application is undeployed Tomcat logs a warning that the application has created a ThreadLocal and not removed it:
SEVERE: The web application [/sandbox] created a ThreadLocal with key of type [null] (value [com.sun.jersey.core.impl.provider.xml.ThreadLocalSingletonContextProvider$1@15ce9c4]) and a value of type [com.sun.org.apache.xerces.internal.jaxp.SAXParserFactoryImpl] (value [com.sun.org.apache.xerces.internal.jaxp.SAXParserFactoryImpl@f76983]) but failed to remove it when the web application was stopped. This is very likely to create a memory leak.
After deploying and undeploying the app several times Tomcat runs out of PermGen space.