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

User · Answer

This problem appears when we are using any third party solution, without using the handlers for the cleanup activitiy. For me this was happening for EhCache. We were using EhCache in our project for caching. And often we used to see following error in the logs

 SEVERE: The web application [/products] appears to have started a thread named [products_default_cache_configuration] but has failed to stop it. This is very likely to create a memory leak.
Aug 07, 2017 11:08:36 AM org.apache.catalina.loader.WebappClassLoader clearReferencesThreads
SEVERE: The web application [/products] appears to have started a thread named [Statistics Thread-products_default_cache_configuration-1] but has failed to stop it. This is very likely to create a memory leak.

And we often noticed tomcat failing for OutOfMemory error during development where we used to do backend changes and deploy the application multiple times for reflecting our changes.

This is the fix we did

<listener>
  <listener-class>
     net.sf.ehcache.constructs.web.ShutdownListener
  </listener-class>
</listener>

So point I am trying to make is check the documentation of the third party libraries which you are using. They should be providing some mechanisms to clean up the threads during shutdown. Which you need to use in your application. No need to re-invent the wheel unless its not provided by them. The worst case is to provide your own implementation.

Reference for EHCache Shutdown http://www.ehcache.org/documentation/2.8/operations/shutdown.html

User · Answer

The key  Transactional Resources  looks like you are talking to the database without a proper transaction  Make sure transaction management is configured properly and no invocation path to the DAO exists that doesn t run under a  Transactional annotation  This can easily happen when you configured transaction management on the Controller level but are invoking DAOs in a timer or are using  PostConstruct annotations  I wrote it up here http   georgovassilis blogspot nl 2014 01 tomcat-spring-and-memory-leaks-when html  Edit  It looks like this is  also   a bug with spring-data-jpa which has been fixed with v1 4 3  I looked it up in the spring-data-jpa sources of LockModeRepositoryPostProcessor which sets the  Transactional Resources  key  In 1 4 3 it also clears the key again

User · Answer

Sometimes this has to do with configuration changes  When we upgraded from Tomncat 6 0 14 to 6 0 26  we had seen something similar  here is the solution http   www skill-guru com blog 2010 08 22 tomcat-6-0-26-shutdown-reports-a-web-application-created-a-threadlocal-threadlocal-has-been-forcibly-removed

User · Answer

I added the following to  PreDestroy method in my CDI  ApplicationScoped bean  and when I shutdown TomEE 1 6 0  tomcat7 0 39  as of today   it clears the thread locals         To change this template  choose Tools   Templates    and open the template in the editor      package pf   import java lang ref WeakReference  import java lang reflect Array  import java lang reflect Field   import org slf4j Logger  import org slf4j LoggerFactory              author Administrator        google-gson issue   402  Memory Leak in web application  comment   25    https   code google com p google-gson issues detail id 402     public class ThreadLocalImmolater        final Logger logger   LoggerFactory getLogger ThreadLocalImmolater class        Boolean debug       public ThreadLocalImmolater             debug   true             public Integer immolate             int count   0          try               final Field threadLocalsField   Thread class getDeclaredField  threadLocals                threadLocalsField setAccessible true               final Field inheritableThreadLocalsField   Thread class getDeclaredField  inheritableThreadLocals                inheritableThreadLocalsField setAccessible true               for  final Thread thread   Thread getAllStackTraces   keySet                          count    clear threadLocalsField get thread                        count    clear inheritableThreadLocalsField get thread                              logger info  immolated     count     values in ThreadLocals              catch  Exception e                throw new Error  ThreadLocalImmolater immolate     e                     return count             private int clear final Object threadLocalMap  throws Exception           if  threadLocalMap    null                  return 0          int count   0          final Field tableField   threadLocalMap getClass   getDeclaredField  table            tableField setAccessible true           final Object table   tableField get threadLocalMap           for  int i   0  length   Array getLength table   i  lt  length    i                final Object entry   Array get table  i               if  entry    null                    final Object threadLocal     WeakReference entry  get                    if  threadLocal    null                        log i  threadLocal                       Array set table  i  null                         count                                                    return count             private void log int i  final Object threadLocal            if   debug                return                    if  threadLocal getClass      null  amp  amp              threadLocal getClass   getEnclosingClass      null  amp  amp              threadLocal getClass   getEnclosingClass   getName      null                 logger info  threadLocalMap     i                                   threadLocal getClass   getEnclosingClass   getName                       else if  threadLocal getClass      null  amp  amp                   threadLocal getClass   getName      null                logger info  threadLocalMap     i           threadLocal getClass   getName                       else               logger info  threadLocalMap     i       cannot identify threadlocal class name

User · Answer

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

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

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