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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:+IgnoreUnrecognizedVMOptions -XX:+EliminateAutoBox -XX:AutoBoxCacheMax=20000 HashMapCloneLeak
31  */
32 
33 package test.java.util.HashMap;
34 
35 import java.util.HashMap;
36 import java.lang.ref.WeakReference;
37 
38 public class HashMapCloneLeak {
39 
40     static WeakReference<Object> wr = null;
41 
42     // helper method to keep testObject and map out of main method's scope
makeMap()43     private static HashMap<Integer, Object> makeMap() {
44         HashMap<Integer, Object> map = new HashMap<Integer, Object>();
45         Object testObject = new Object();
46         wr = new WeakReference<Object>(testObject);
47         map.put(42, testObject);
48         return map;
49     }
50 
main(String[] args)51     public static void main(String[] args) throws Exception {
52         HashMap<Integer, Object> hm = makeMap();
53         hm = (HashMap<Integer, Object>)hm.clone();
54         hm.clear();
55         // There should no longer be a strong reference to testObject
56         // the WeakReference should be nulled out by GC. If not,
57         // we will hang here until timed out by the test harness.
58         Object[] chain = null;
59         while (wr.get() != null) {
60             try {
61                 Object[] allocate = new Object[1000000];
62                 allocate[0] = chain;
63                 chain = allocate;
64             } catch (OutOfMemoryError oome) {
65                 chain = null;
66             }
67             System.gc();
68             Thread.sleep(100);
69         }
70     }
71 
72 }
73