Is this very likely to create a memory leak in Tomcat?

Question

I configured tomcat to work with a different external open source.

However, after the tomcat is running for a few minutes I get:

SEVERE: The web application [/MyProject] created a ThreadLocal with key of type [java.lang.ThreadLocal] (value [java.lang.ThreadLocal@1b3f02f]) and a value of type [org.apache.axis.MessageContext] (value [org.apache.axis.MessageContext@5dbd4e]) but failed to remove it when the web application was stopped. This is very likely to create a memory leak.

What could cause it?

Where do I have to look? Could it be datapooling on Tomcat?

And what does it mean Threads in Tomcat?

EDITED

Here is my full trace. The application seems to reloads its context while it's still running - and I don't know why!

Mar 13, 2011 10:56:12 PM org.apache.catalina.core.StandardContext reload INFO: Reloading this Context has started Mar 13, 2011 10:56:12 PM org.apache.catalina.core.StandardWrapper unload INFO: Waiting for 1 instance(s) to be deallocated Mar 13, 2011 10:56:13 PM org.apache.catalina.core.StandardWrapper unload INFO: Waiting for 1 instance(s) to be deallocated Mar 13, 2011 10:56:14 PM org.apache.catalina.core.StandardWrapper unload INFO: Waiting for 1 instance(s) to be deallocated Mar 13, 2011 10:56:14 PM org.apache.catalina.core.ApplicationContext log INFO: Closing Spring root WebApplicationContext Mar 13, 2011 10:56:15 PM org.apache.catalina.loader.WebappClassLoader clearReferencesJdbc SEVERE: The web application [/MyProject] registered the JBDC driver [com.mysql.jdbc.Driver] but failed to unregister it when the web application was stopped. To prevent a memory leak, the JDBC Driver has been forcibly unregistered. Mar 13, 2011 10:56:15 PM org.apache.catalina.loader.WebappClassLoader clearReferencesJdbc SEVERE: The web application [/MyProject] registered the JBDC 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. Mar 13, 2011 10:56:15 PM org.apache.catalina.loader.WebappClassLoader clearReferencesThreads SEVERE: The web application [/MyProject] appears to have started a thread named [NioSocketAcceptor-1] but has failed to stop it. This is very likely to create a memory leak. Mar 13, 2011 10:56:15 PM org.apache.catalina.loader.WebappClassLoader clearReferencesThreads SEVERE: The web application [/MyProject] appears to have started a thread named [NioProcessor-1] but has failed to stop it. This is very likely to create a memory leak. Mar 13, 2011 10:56:15 PM org.apache.catalina.loader.WebappClassLoader clearReferencesThreads SEVERE: The web application [/MyProject] appears to have started a thread named [NioProcessor-4] but has failed to stop it. This is very likely to create a memory leak. Mar 13, 2011 10:56:15 PM org.apache.catalina.loader.WebappClassLoader clearReferencesThreads SEVERE: The web application [/MyProject] appears to have started a thread named [bitronix-disk-force-batcher] but has failed to stop it. This is very likely to create a memory leak. Mar 13, 2011 10:56:15 PM org.apache.catalina.loader.WebappClassLoader clearReferencesThreads SEVERE: The web application [/MyProject] appears to have started a thread named [bitronix-scheduler] but has failed to stop it. This is very likely to create a memory leak. Mar 13, 2011 10:56:15 PM org.apache.catalina.loader.WebappClassLoader clearReferencesThreads SEVERE: The web application [/MyProject] is still processing a request that has yet to finish. This is very likely to create a memory leak. You can control the time allowed for requests to finish by using the unloadDelay attribute of the standard Context implementation. Mar 13, 2011 10:56:15 PM org.apache.catalina.loader.WebappClassLoader clearReferencesThreads SEVERE: The web application [/MyProject] appears to have started a thread named [NioProcessor-7] but has failed to stop it. This is very likely to create a memory leak. Mar 13, 2011 10:56:15 PM org.apache.catalina.loader.WebappClassLoader clearReferencesThreads SEVERE: The web application [/MyProject] appears to have started a thread named [NioProcessor-2] but has failed to stop it. This is very likely to create a memory leak. Mar 13, 2011 10:56:15 PM org.apache.catalina.loader.WebappClassLoader clearThreadLocalMap SEVERE: The web application [/MyProject] created a ThreadLocal with key of type [java.lang.ThreadLocal] (value [java.lang.ThreadLocal@1b5a8e1]) and a value of type [org.mvel2.debug.DebuggerContext] (value [org.mvel2.debug.DebuggerContext@16259fd]) but failed to remove it when the web application was stopped. This is very likely to create a memory leak. Mar 13, 2011 10:56:15 PM org.apache.catalina.loader.WebappClassLoader clearThreadLocalMap SEVERE: The web application [/MyProject] created a ThreadLocal with key of type [org.apache.axis.utils.XMLUtils.ThreadLocalDocumentBuilder] (value [org.apache.axis.utils.XMLUtils$ThreadLocalDocumentBuilder@84b0b4]) and a value of type [com.sun.org.apache.xerces.internal.jaxp.DocumentBuilderImpl] (value [com.sun.org.apache.xerces.internal.jaxp.DocumentBuilderImpl@16d2cfa]) but failed to remove it when the web application was stopped. This is very likely to create a memory leak. Mar 13, 2011 10:56:15 PM org.apache.catalina.loader.WebappClassLoader clearThreadLocalMap SEVERE: The web application [/MyProject] created a ThreadLocal with key of type [null] (value [com.sun.faces.util.Util$1@16bbac9]) and a value of type [java.util.HashMap] (value [{com.sun.faces.patternCache={ = }}]) but failed to remove it when the web application was stopped. This is very likely to create a memory leak. Mar 13, 2011 10:56:15 PM org.apache.catalina.loader.WebappClassLoader clearThreadLocalMap SEVERE: The web application [/MyProject] created a ThreadLocal with key of type [java.lang.ThreadLocal] (value [java.lang.ThreadLocal@1b3f02f]) and a value of type [org.apache.axis.MessageContext] (value [org.apache.axis.MessageContext@5dbd4e]) but failed to remove it when the web application was stopped. This is very likely to create a memory leak. Mar 13, 2011 10:56:15 PM org.apache.catalina.loader.WebappClassLoader clearThreadLocalMap SEVERE: The web application [/MyProject] created a ThreadLocal with key of type [org.apache.axis.utils.XMLUtils.ThreadLocalDocumentBuilder] (value [org.apache.axis.utils.XMLUtils$ThreadLocalDocumentBuilder@84b0b4]) and a value of type [com.sun.org.apache.xerces.internal.jaxp.DocumentBuilderImpl] (value [com.sun.org.apache.xerces.internal.jaxp.DocumentBuilderImpl@378584]) but failed to remove it when the web application was stopped. This is very likely to create a memory leak. Mar 13, 2011 10:56:15 PM org.apache.catalina.loader.WebappClassLoader clearThreadLocalMap SEVERE: The web application [/MyProject] created a ThreadLocal with key of type [org.springframework.core.NamedThreadLocal] (value [Transactional resources]) and a value of type [java.util.HashMap] (value [{org.hibernate.impl.SessionFactoryImpl@ccc27b=org.springframework.orm.hibernate3.SessionHolder@4f6ada}]) but failed to remove it when the web application was stopped. This is very likely to create a memory leak. Mar 13, 2011 10:56:15 PM org.apache.catalina.loader.WebappClassLoader clearThreadLocalMap SEVERE: The web application [/MyProject] created a ThreadLocal with key of type [null] (value [com.sun.faces.application.ApplicationAssociate$1@1f01fcf]) and a value of type [com.sun.faces.application.ApplicationAssociate] (value [com.sun.faces.application.ApplicationAssociate@1b85528]) but failed to remove it when the web application was stopped. This is very likely to create a memory leak. 2011-03-13 22:57:27,734 ERROR (            ContextLoader.java:220)     - Context initialization failed org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'transactionManager' defined in class path resource [applicationContext-hibernate.xml]: Cannot resolve reference to bean 'sessionFactory' while setting bean property 'sessionFactory'; nested exception is org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'sessionFactory' defined in class path resource [applicationContext-hibernate.xml]: Invocation of init method failed; nested exception is java.lang.OutOfMemoryError: Java heap space     at org.springframework.beans.factory.support.BeanDefinitionValueResolver.resolveReference(BeanDefinitionValueResolver.java:328)     at org.springframework.beans.factory.support.BeanDefinitionValueResolver.resolveValueIfNecessary(BeanDefinitionValueResolver.java:106)     at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.applyPropertyValues(AbstractAutowireCapableBeanFactory.java:1325) 

Answer 1

The message is actually pretty clear: something creates a ThreadLocal with value of type org.apache.axis.MessageContext - this is a great hint. It most likely means that Apache Axis framework forgot/failed to cleanup after itself. The same problem occurred for instance in Logback. You shouldn't bother much, but reporting a bug to Axis team might be a good idea.

Tomcat reports this error because the ThreadLocals are created per HTTP worker threads. Your application is undeployed but HTTP threads remain - and these ThreadLocals as well. This may lead to memory leaks (org.apache.axis.MessageContext can't be unloaded) and some issues when these threads are reused in the future.

For details see: http://wiki.apache.org/tomcat/MemoryLeakProtection