1 /*
2 * Licensed under the GPL License. You may not use this file except in compliance with the License.
3 * You may obtain a copy of the License at
4 *
5 * https://www.gnu.org/licenses/old-licenses/gpl-2.0.html
6 *
7 * THIS PACKAGE IS PROVIDED "AS IS" AND WITHOUT ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING,
8 * WITHOUT LIMITATION, THE IMPLIED WARRANTIES OF MERCHANTIBILITY AND FITNESS FOR A PARTICULAR
9 * PURPOSE.
10 */
11 package psiprobe;
12
13 import javax.imageio.ImageIO;
14 import javax.servlet.ServletContextEvent;
15 import javax.servlet.ServletContextListener;
16 import javax.servlet.annotation.WebListener;
17
18 import org.slf4j.Logger;
19 import org.slf4j.LoggerFactory;
20
21 /**
22 * Prevents a classloader leak.
23 *
24 * <p>
25 * As suggested by: <a href="https://cdivilly.wordpress.com/2012/04/23/permgen-memory-leak/">Colm
26 * Divilly</a>
27 */
28 @WebListener
29 public class AwtAppContextClassloaderListener implements ServletContextListener {
30
31 /** The Constant logger. */
32 private static final Logger logger =
33 LoggerFactory.getLogger(AwtAppContextClassloaderListener.class);
34
35 /**
36 * Forces the {@code sun.awt.AppContext} singleton to be created and initialized when the context
37 * is initialized.
38 *
39 * @param sce the event containing the context being initialized
40 */
41 @Override
42 public void contextInitialized(ServletContextEvent sce) {
43 try {
44 final ClassLoader active = Thread.currentThread().getContextClassLoader();
45 try {
46 // Find the root classloader
47 ClassLoader root = active;
48 while (root.getParent() != null) {
49 root = root.getParent();
50 }
51 // Temporarily make the root class loader the active class loader
52 Thread.currentThread().setContextClassLoader(root);
53 /*
54 * Forces the sun.awt.AppContext singleton to be created and initialized. Call
55 * ImageIO.getCacheDirectory() to avoid direct call to Oracle JVM internal class
56 * sun.awt.AppContext. Same solution as in
57 * org.apache.catalina.core.JreMemoryLeakPreventionListener which is optional on Tomcat
58 * 1.7.0_02 or greater.
59 */
60 ImageIO.getCacheDirectory();
61 } finally {
62 // restore the class loader
63 Thread.currentThread().setContextClassLoader(active);
64 }
65 logger.info("AwtAppContextClassloaderListener Initialized");
66 } catch (Exception e) {
67 logger.error("Failed to address PermGen leak.", e);
68 }
69 }
70
71 @Override
72 public void contextDestroyed(ServletContextEvent sce) {
73 // Not Implemented
74 }
75
76 }