1 /*
   2  * Copyright (c) 2000, Oracle and/or its affiliates. All rights reserved.
   3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   4  *
   5  * This code is free software; you can redistribute it and/or modify it
   6  * under the terms of the GNU General Public License version 2 only, as
   7  * published by the Free Software Foundation.
   8  *
   9  * This code is distributed in the hope that it will be useful, but WITHOUT
  10  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  11  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  12  * version 2 for more details (a copy is included in the LICENSE file that
  13  * accompanied this code).
  14  *
  15  * You should have received a copy of the GNU General Public License version
  16  * 2 along with this work; if not, write to the Free Software Foundation,
  17  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  18  *
  19  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  20  * or visit www.oracle.com if you need additional information or have any
  21  * questions.
  22  */
  23 
  24 /* @test
  25  * @bug 4332184
  26  * @summary Ensure that ObjectOutputStream properly releases strong references
  27  *          to written objects when reset() is called.
  28  */
  29 
  30 import java.io.*;
  31 import java.lang.ref.WeakReference;
  32 import java.util.ArrayList;
  33 import java.util.Iterator;
  34 import java.util.List;
  35 
  36 public class ClearHandleTable {
  37     private static final int TIMES = 1000;
  38 
  39     public static void main(String[] args) throws Exception {
  40         final int nreps = 100;
  41         ObjectOutputStream oout =
  42             new ObjectOutputStream(new ByteArrayOutputStream());
  43         List<WeakReference<?>> refs = new ArrayList<>(nreps);
  44 
  45         for (int i = 0; i < nreps; i++) {
  46             String str = new String("blargh");
  47             oout.writeObject(str);
  48             refs.add(new WeakReference<Object>(str));
  49         }
  50 
  51         oout.reset();

  52 
  53         int count = 0;
  54         for (int i=0; i<TIMES; i++) {
  55             // relying on, possibly multiple, System.gc calls to clear weak references
  56             System.gc();
  57 
  58             Iterator<WeakReference<?>> itr = refs.iterator();
  59             while(itr.hasNext()) {
  60                 WeakReference<?> ref = itr.next();
  61                 if (ref.get() == null) {
  62                     itr.remove();
  63                 }
  64             }
  65             if (refs.isEmpty())
  66                 break;
  67             Thread.sleep(20);
  68             count++;
  69             if (count % 10 == 0)
  70                 System.out.println("Looping " + count + " times");
  71         }
  72 
  73         if (!refs.isEmpty()) {
  74             throw new Error("failed to garbage collect object");





  75         }
  76     }
  77 }
--- EOF ---