1 /*
   2  * Copyright (c) 2013, 2018, 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 /**
  25  * @test
  26  * @bug 7042126
  27  * @summary Verify that we do not leak contents when we clone a HashMap
  28  * @author david.buck@oracle.com
  29  * @run main/othervm HashMapCloneLeak
  30  * @run main/othervm -XX:+EliminateAutoBox -XX:AutoBoxCacheMax=20000 HashMapCloneLeak
  31  */
  32 
  33 import java.util.HashMap;
  34 import java.lang.ref.WeakReference;
  35 
  36 public class HashMapCloneLeak {
  37 
  38     static WeakReference<Object> wr = null;
  39 
  40     // helper method to keep testObject and map out of main method's scope
  41     private static HashMap<Integer, Object> makeMap() {
  42         HashMap<Integer, Object> map = new HashMap<Integer, Object>();
  43         Object testObject = new Object();
  44         wr = new WeakReference<Object>(testObject);
  45         map.put(42, testObject);
  46         return map;
  47     }
  48 
  49     public static void main(String[] args) throws Exception {
  50         HashMap<Integer, Object> hm = makeMap();
  51         hm = (HashMap<Integer, Object>)hm.clone();
  52         hm.clear();
  53         // There should no longer be a strong reference to testObject
  54         // the WeakReference should be nulled out by GC. If not,
  55         // we will hang here until timed out by the test harness.
  56         Object[] chain = null;
  57         while (wr.get() != null) {
  58             try {
  59                 Object[] allocate = new Object[1000000];
  60                 allocate[0] = chain;
  61                 chain = allocate;
  62             } catch (OutOfMemoryError oome) {
  63                 chain = null;
  64             }
  65             System.gc();
  66             Thread.sleep(100);
  67         }
  68     }
  69 
  70 }