Class memory allocation not released after undeployment.

Description

My CRUD application is based on Manageable entity + Spring + Hibernate + MySQL. This application is deployed on Jboss 4.0.4GA or Tomcat 5.5.17.

My CRUD based application doesn't release the memory allocated to the application specifc, spring, hibernate and cglib classes.

The problem occurs on both environments under Windows. This problem occurs violently with Sun SDK (PermGen error) and more silently with BEA JRockit SDK (Heap error).

This problem occurs after 6-10 Deploy/Undeploy cycles with small heap size.

I partially track down the problem :

  • Enumeration Application classes contain cyclic references.Those cycle have to be broken at undeployment time

  • Spring framework requires to explicitely release resources at undeployment time. This is currently not done.

  • Hibernate also require to explicitely release resource at undeployment time. This is currently not done.

  • Cglib depends of Spring resource release, without Spring release, no Cglib release

Even after those closures, all resources are not recovered :

  • all enumeration application classes are recoverd by the GC.

  • 90 % of Spring+Hibernate+Cglib class have been recovered by the GC.

  • Application independant classes, kernel of Spring and Hibernate, are not recovered by GC. Those infrastructure classes are reused by the next deployment cycle.

  • Few application class remain in memory and generate a small memory leak.

If anyone is interested to continue this cleaning :

Enumeration patch :
[code]
— R:\andromda-src-3.2-SNAPSHOT-20061001\cartridges\andromda-java\src\templates\java\Enumeration.vsl Mon Oct 02 11:38:39 2006
+++ R:\andromda-src-3.2-SNAPSHOT-20061001-fork\cartridges\andromda-java\src\templates\java\Enumeration.vsl Thu Oct 05 15:49:51 2006
@@ -43,7 +43,7 @@
/**
$literal.getDocumentation(" * ")
*/

  • public static final $enumeration.name $literal.name = new ${enumeration.name}($literal.enumerationValue);
    + public static $enumeration.name $literal.name = new ${enumeration.name}($literal.enumerationValue);


#end
private $enumeration.literalType.fullyQualifiedName value;
@@ -119,7 +119,7 @@
*/
public static java.util.List${literalsTemplateType} literals()
{

  • return literals;
    + return java.util.Collections.unmodifiableList(literals);
    }


/**
@@ -131,7 +131,23 @@
*/
public static java.util.List${namesTemplateType} names()
{

  • return names;
    + return java.util.Collections.unmodifiableList(names);
    + }
    +
    + /**
    + * This method HAS TO BE CALLED during undeployment. This method
    + * releases collection instances containing cyclic references
    + * for allowing GC during undeployment. Cyclic reference occurs directly
    + * or thru indirect Collection usage.
    + */
    + public static void clear()
    + {
    +#foreach ($literal in $enumeration.literals)
    + $literal.name = null;
    +#end
    + if (values != null) values.clear();
    + if (literals != null) literals.clear();
    + if (names != null) names.clear();
    }


/**
@@ -198,7 +214,5 @@
literals.add($value);
names.add("$literal.name");
#end

  • literals = java.util.Collections.unmodifiableList(literals);

  • names = java.util.Collections.unmodifiableList(names);
    }
    }
    /code

and call clear() from your servlet undeploy listener

Hibernate cleaning without spring:
[url]http://www.hibernate.org/114.html/url

[code]// license-header java merge-point
//
// Attention: Generated code! Do not modify by hand!
// Generated by: HibernateUtil.vsl in andromda-hibernate-cartridge.
//
#set ($generatedFile = "${stringUtils.replace($enumeration.packageName, '.', '/')}/HibernateUtil.java")
#if ($stringUtils.isNotBlank($enumeration.packageName))
package $enumeration.packageName;
#end

//TODO : Code generation for JNDI : To obtain thru jndi reference Hibernate context
//import javax.naming.*;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;

import ${hibernateUtils.hibernatePackage}.cfg.Configuration;
import ${hibernateUtils.hibernatePackage}.Interceptor;
import ${hibernateUtils.hibernatePackage}.Session;
import ${hibernateUtils.hibernatePackage}.SessionFactory;
import ${hibernateUtils.hibernatePackage}.Transaction;
import ${hibernateUtils.hibernatePackage}.HibernateException;

/**

  • Basic Hibernate helper class, handles SessionFactory, Session and Transaction.

  • <p>

  • Uses a static initializer for the initial SessionFactory creation

  • and holds Session and Transactions in thread local variables. All

  • exceptions are wrapped in an unchecked HibernateException.
    *

  • @author christian@hibernate.org
    */
    public class HibernateUtil {

private static Log log = LogFactory.getLog(HibernateUtil.class);

private static Configuration configuration;
private static SessionFactory sessionFactory;
private static final ThreadLocal threadSession = new ThreadLocal();
private static final ThreadLocal threadTransaction = new ThreadLocal();
private static final ThreadLocal threadInterceptor = new ThreadLocal();

// Create the initial SessionFactory from the default configuration files
static {
try {
log.debug("Create the initial SessionFactory from the default configuration files.");
configuration = new Configuration();
sessionFactory = configuration.configure().buildSessionFactory();
// We could also let Hibernate bind it to JNDI:
// configuration.configure().buildSessionFactory()
} catch (Throwable ex) {
// We have to catch Throwable, otherwise we will miss
// NoClassDefFoundError and other subclasses of Error
log.error("Building SessionFactory failed.", ex);
throw new ExceptionInInitializerError(ex);
}
}

/**

  • Returns the SessionFactory used for this static class.
    *
    * @return SessionFactory
    */
    public static SessionFactory getSessionFactory() {
    /* Instead of a static variable, use JNDI:
    SessionFactory sessions = null;
    try {
    Context ctx = new InitialContext();
    String jndiName = "java:hibernate/HibernateFactory";
    sessions = (SessionFactory)ctx.lookup(jndiName);
    } catch (NamingException ex) {
    throw new HibernateException(ex);
    }
    return sessions;
    */
    return sessionFactory;
    }

/**

  • Returns the original Hibernate configuration.
    *
    * @return Configuration
    */
    public static Configuration getConfiguration() {
    return configuration;
    }

/**

  • Rebuild the SessionFactory with the static Configuration.
    *
    */
    public static void rebuildSessionFactory()
    throws HibernateException {
    synchronized(sessionFactory) {
    try {
    sessionFactory = getConfiguration().buildSessionFactory();
    } catch (Exception ex) {
    throw new HibernateException(ex);
    }
    }
    }

/**

  • Rebuild the SessionFactory with the given Hibernate Configuration.
    *
    * @param cfg
    */
    public static void rebuildSessionFactory(Configuration cfg)
    throws HibernateException {
    synchronized(sessionFactory) {
    try {
    sessionFactory = cfg.buildSessionFactory();
    configuration = cfg;
    } catch (Exception ex) {
    throw new HibernateException(ex);
    }
    }
    }

/**

  • Retrieves the current Session local to the thread.
    * <p/>
    * If no Session is open, opens a new Session for the running thread.
    *
    * @return Session
    */
    public static Session getSession()
    throws HibernateException {
    Session s = (Session) threadSession.get();
    try {
    if (s == null) {
    log.debug("Opening new Session for this thread.");
    if (getInterceptor() != null) {
    log.debug("Using interceptor: " + getInterceptor().getClass());
    s = getSessionFactory().openSession(getInterceptor());
    } else {
    s = getSessionFactory().openSession();
    }
    threadSession.set(s);
    }
    } catch (HibernateException ex) {
    throw new HibernateException(ex);
    }
    return s;
    }

/**

  • Closes the Session local to the thread.
    */
    public static void closeSession()
    throws HibernateException {
    try {
    Session s = (Session) threadSession.get();
    threadSession.set(null);
    if (s != null && s.isOpen()) {
    log.debug("Closing Session of this thread.");
    s.close();
    }
    } catch (HibernateException ex) {
    throw new HibernateException(ex);
    }
    }

/**

  • Start a new database transaction.
    */
    public static void beginTransaction()
    throws HibernateException {
    Transaction tx = (Transaction) threadTransaction.get();
    try {
    if (tx == null) {
    log.debug("Starting new database transaction in this thread.");
    tx = getSession().beginTransaction();
    threadTransaction.set(tx);
    }
    } catch (HibernateException ex) {
    throw new HibernateException(ex);
    }
    }

/**

  • Commit the database transaction.
    */
    public static void commitTransaction()
    throws HibernateException {
    Transaction tx = (Transaction) threadTransaction.get();
    try {
    if ( tx != null && !tx.wasCommitted()
    && !tx.wasRolledBack() ) {
    log.debug("Committing database transaction of this thread.");
    tx.commit();
    }
    threadTransaction.set(null);
    } catch (HibernateException ex) {
    rollbackTransaction();
    throw new HibernateException(ex);
    }
    }

/**

  • Commit the database transaction.
    */
    public static void rollbackTransaction()
    throws HibernateException {
    Transaction tx = (Transaction) threadTransaction.get();
    try {
    threadTransaction.set(null);
    if ( tx != null && !tx.wasCommitted() && !tx.wasRolledBack() ) {
    log.debug("Tyring to rollback database transaction of this thread.");
    tx.rollback();
    }
    } catch (HibernateException ex) {
    throw new HibernateException(ex);
    } finally {
    closeSession();
    }
    }

/**

  • Reconnects a Hibernate Session to the current Thread.
    *
    * @param session The Hibernate Session to be reconnected.
    */
    public static void reconnect(Session session)
    throws HibernateException {
    try {
    session.reconnect();
    threadSession.set(session);
    } catch (HibernateException ex) {
    throw new HibernateException(ex);
    }
    }

/**

  • Disconnect and return Session from current Thread.
    *
    * @return Session the disconnected Session
    */
    public static Session disconnectSession()
    throws HibernateException {

Session session = getSession();
try {
threadSession.set(null);
if (session.isConnected() && session.isOpen())
session.disconnect();
} catch (HibernateException ex) {
throw new HibernateException(ex);
}
return session;
}

/**

  • Register a Hibernate interceptor with the current thread.
    * <p>
    * Every Session opened is opened with this interceptor after
    * registration. Has no effect if the current Session of the
    * thread is already open, effective on next close()/getSession().
    */
    public static void registerInterceptor(Interceptor interceptor) {
    threadInterceptor.set(interceptor);
    }

private static Interceptor getInterceptor() {
Interceptor interceptor =
(Interceptor) threadInterceptor.get();
return interceptor;
}

}
/code

and call ${enumeration.packageName}.HibernateUtil.getSessionFactory(); // Just call the static initializer of that class
during servlet initialisation and ${enumeration.packageName}.HibernateUtil.getSessionFactory().close(); // Free all resources
during servlet destruction

Spring cleaning :
[url]http://ego.developpez.com/spring//url chapter 3.2.2
[url]http://www.springframework.org/docs/reference/webintegration.html/url

[code]
<listener>
<listener-class>org.springframework.web.context.ContextLoaderListener</listener-class>
</listener>/code

Similar problem should occur with JSF because a specific Listener exists [url]http://www.esup-portail.org/consortium/espace/Normes_1C/portlet-spring/esup-portlet-spring-JSF.html/url

[code]
<listener>
<listener-class>org.apache.myfaces.webapp.StartupServletContextListener</listener-class>
</listener>/code

To monitor your Sun JVM :

To monitor your JRockit JVM :

Environment

SNAPSHOT

Assignee

Former user

Reporter

PierreP

Labels

None

Components

Affects versions

Priority

Blocker
Configure