353095 - maven-jetty-plugin: PermGen leak due to javax.el.BeanELResolver

Also found that java beans can be leaked via java.beans.Introspector so fixed that too.

jetty-servlet/src/main/java/org/eclipse/jetty/servlet/listener/ELContextCleaner.java

@@ -0,0 +1,120 @@
+// ========================================================================
+// Copyright (c) 2011 Mort Bay Consulting Pty. Ltd.
+// ------------------------------------------------------------------------
+// All rights reserved. This program and the accompanying materials
+// are made available under the terms of the Eclipse Public License v1.0
+// and Apache License v2.0 which accompanies this distribution.
+// The Eclipse Public License is available at
+// http://www.eclipse.org/legal/epl-v10.html
+// The Apache License v2.0 is available at
+// http://www.opensource.org/licenses/apache2.0.php
+// You may elect to redistribute this code under either of these licenses.
+// ========================================================================
+
+package org.eclipse.jetty.servlet.listener;
+
+import java.lang.reflect.Field;
+import java.lang.reflect.InvocationTargetException;
+import java.lang.reflect.Method;
+import java.util.Iterator;
+import java.util.concurrent.ConcurrentHashMap;
+
+import javax.servlet.ServletContextEvent;
+import javax.servlet.ServletContextListener;
+
+import org.eclipse.jetty.util.Loader;
+import org.eclipse.jetty.util.log.Log;
+
+/**
+ * ELContextCleaner
+ *
+ * Clean up BeanELResolver when the context is going out
+ * of service:
+ * 
+ * See http://java.net/jira/browse/GLASSFISH-1649
+ * See https://bugs.eclipse.org/bugs/show_bug.cgi?id=353095
+ */
+public class ELContextCleaner implements ServletContextListener
+{
+
+    public void contextInitialized(ServletContextEvent sce)
+    {
+    }
+
+    public void contextDestroyed(ServletContextEvent sce)
+    {
+        try
+        {
+            //Check that the BeanELResolver class is on the classpath
+            Class beanELResolver = Loader.loadClass(this.getClass(), "javax.el.BeanELResolver");
+
+            //Get a reference via reflection to the properties field which is holding class references
+            Field field = getField(beanELResolver);
+
+            //Get rid of references
+            purgeEntries(field);
+            
+            Log.info("javax.el.BeanELResolver purged");
+        }
+        
+        catch (ClassNotFoundException e)
+        {
+            //BeanELResolver not on classpath, ignore
+        }
+        catch (SecurityException e)
+        {
+            Log.warn("Cannot purge classes from javax.el.BeanELResolver", e);
+        }
+        catch (IllegalArgumentException e)
+        {
+            Log.warn("Cannot purge classes from javax.el.BeanELResolver", e);
+        }
+        catch (IllegalAccessException e)
+        {
+            Log.warn("Cannot purge classes from javax.el.BeanELResolver", e);
+        }
+        catch (NoSuchFieldException e)
+        {
+            Log.warn("Cannot purge classes from javax.el.BeanELResolver", e);
+        }
+       
+    }
+
+
+    protected Field getField (Class beanELResolver) 
+    throws SecurityException, NoSuchFieldException
+    {
+        if (beanELResolver == null)
+            return  null;
+
+        return beanELResolver.getDeclaredField("properties");
+    }
+
+    protected void purgeEntries (Field properties) 
+    throws IllegalArgumentException, IllegalAccessException
+    {
+        if (properties == null)
+            return;
+
+        if (!properties.isAccessible())
+            properties.setAccessible(true);
+
+        ConcurrentHashMap map = (ConcurrentHashMap) properties.get(null);
+        if (map == null)
+            return;
+        
+        Iterator<Class> itor = map.keySet().iterator();
+        while (itor.hasNext()) 
+        {
+            Class clazz = itor.next();
+            Log.info("Clazz: "+clazz+" loaded by "+clazz.getClassLoader());
+            if (Thread.currentThread().getContextClassLoader().equals(clazz.getClassLoader()))
+            {
+                itor.remove();  
+                Log.info("removed");
+            }
+            else
+                Log.info("not removed: "+"contextclassloader="+Thread.currentThread().getContextClassLoader()+"clazz's classloader="+clazz.getClassLoader());
+        }
+    }
+}

jetty-servlet/src/main/java/org/eclipse/jetty/servlet/listener/IntrospectorCleaner.java

@@ -0,0 +1,40 @@
+// ========================================================================
+// Copyright (c) 2011 Mort Bay Consulting Pty. Ltd.
+// ------------------------------------------------------------------------
+// All rights reserved. This program and the accompanying materials
+// are made available under the terms of the Eclipse Public License v1.0
+// and Apache License v2.0 which accompanies this distribution.
+// The Eclipse Public License is available at
+// http://www.eclipse.org/legal/epl-v10.html
+// The Apache License v2.0 is available at
+// http://www.opensource.org/licenses/apache2.0.php
+// You may elect to redistribute this code under either of these licenses.
+// ========================================================================
+
+package org.eclipse.jetty.servlet.listener;
+
+import javax.servlet.ServletContextEvent;
+import javax.servlet.ServletContextListener;
+
+/**
+ * IntrospectorCleaner
+ *
+ * Cleans a static cache of Methods held by java.beans.Introspector
+ * class when a context is undeployed.
+ * 
+ * @see java.beans.Introspector
+ */
+public class IntrospectorCleaner implements ServletContextListener
+{
+
+    public void contextInitialized(ServletContextEvent sce)
+    {
+        
+    }
+
+    public void contextDestroyed(ServletContextEvent sce)
+    {
+        java.beans.Introspector.flushCaches();
+    }
+
+}

jetty-webapp/src/main/config/etc/webdefault.xml

@@ -30,6 +30,22 @@
     This file is applied to a Web application before it's own WEB_INF/web.xml file
   </description>
 
+  <!-- ==================================================================== -->
+  <!-- Removes static references to beans from javax.el.BeanELResolver to   -->
+  <!-- ensure webapp classloader can be released on undeploy                -->
+  <!-- ==================================================================== -->
+  <listener>
+   <listener-class>org.eclipse.jetty.servlet.listener.ELContextCleaner</listener-class>
+  </listener>
+  
+  <!-- ==================================================================== -->
+  <!-- Removes static cache of Methods from java.beans.Introspector to      -->
+  <!-- ensure webapp classloader can be released on undeploy                -->
+  <!-- ==================================================================== -->  
+  <listener>
+   <listener-class>org.eclipse.jetty.servlet.listener.IntrospectorCleaner</listener-class>
+  </listener>
+  
 
   <!-- ==================================================================== -->
   <!-- Context params to control Session Cookies                            -->

jetty-webapp/src/main/java/org/eclipse/jetty/webapp/WebAppContext.java

@@ -111,6 +111,7 @@ public class WebAppContext extends ServletContextHandler implements WebAppClassL
         "-org.eclipse.jetty.plus.jaas.",    // don't hide jaas classes
         "-org.eclipse.jetty.websocket.",    // don't hide websocket extension
         "-org.eclipse.jetty.servlet.DefaultServlet", // don't hide default servlet
+        "-org.eclipse.jetty.servlet.listener.", //don't hide useful listeners
         "org.eclipse.jetty."                // hide other jetty classes
     } ;