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1   //
2   //  ========================================================================
3   //  Copyright (c) 1995-2016 Mort Bay Consulting Pty. Ltd.
4   //  ------------------------------------------------------------------------
5   //  All rights reserved. This program and the accompanying materials
6   //  are made available under the terms of the Eclipse Public License v1.0
7   //  and Apache License v2.0 which accompanies this distribution.
8   //
9   //      The Eclipse Public License is available at
10  //      http://www.eclipse.org/legal/epl-v10.html
11  //
12  //      The Apache License v2.0 is available at
13  //      http://www.opensource.org/licenses/apache2.0.php
14  //
15  //  You may elect to redistribute this code under either of these licenses.
16  //  ========================================================================
17  //
18  
19  package org.eclipse.jetty.util.preventers;
20  
21  import java.lang.reflect.Method;
22  
23  /**
24   * GCThreadLeakPreventer
25   *
26   * Prevents a call to sun.misc.GC.requestLatency pinning a webapp classloader
27   * by calling it with a non-webapp classloader. The problem appears to be that
28   * when this method is called, a daemon thread is created which takes the 
29   * context classloader. A known caller of this method is the RMI impl. See
30   * http://stackoverflow.com/questions/6626680/does-java-garbage-collection-log-entry-full-gc-system-mean-some-class-called
31   * 
32   * This preventer will start the thread with the longest possible interval, although
33   * subsequent calls can vary that. Recommend to only use this class if you're doing
34   * RMI.
35   * 
36   * Inspired by Tomcat JreMemoryLeakPrevention.
37   *
38   */
39  public class GCThreadLeakPreventer extends AbstractLeakPreventer
40  {
41      /* ------------------------------------------------------------ */
42      /** 
43       * @see org.eclipse.jetty.util.preventers.AbstractLeakPreventer#prevent(java.lang.ClassLoader)
44       */
45      @Override
46      public void prevent(ClassLoader loader)
47      {
48          try
49          {
50              Class<?> clazz = Class.forName("sun.misc.GC");
51              Method requestLatency = clazz.getMethod("requestLatency", new Class[] {long.class});
52              requestLatency.invoke(null, Long.valueOf(Long.MAX_VALUE-1));
53          }
54          catch (ClassNotFoundException e)
55          {
56              LOG.ignore(e);
57          }
58          catch (Exception e)
59          {
60              LOG.warn(e);
61          }
62      }
63  
64  }