1 /*
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3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4  *
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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
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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
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22  */
23 
24 /* @test
25  * @bug 8014890
26  * @summary Verify that a race between ReferenceQueue.enqueue() and poll() does not occur.
27  * @author thomas.schatzl@oracle.com
28  * @run main/othervm -Xmx10M EnqueuePollRace
29  */
30 package test.java.lang.ref;
31 
32 import java.lang.ref.*;
33 
34 import org.testng.annotations.Test;
35 
36 public class EnqueuePollRaceTest {
37 
38     @Test
test()39     public void test() throws Exception {
40         new WeakRef().run();
41         // System.out.println("Test passed.");
42     }
43 
44     static class WeakRef {
45         ReferenceQueue<Object> queue = new ReferenceQueue<Object>();
46         final int numReferences = 100;
47         final Reference refs[] = new Reference[numReferences];
48         final int iterations = 1000;
49 
run()50         void run() throws InterruptedException {
51             for (int i = 0; i < iterations; i++) {
52                 queue = new ReferenceQueue<Object>();
53 
54                 for (int j = 0; j < refs.length; j++) {
55                     refs[j] = new WeakReference(new Object(), queue);
56                 }
57 
58                 System.gc(); // enqueues references into the list of discovered references
59 
60                 // now manually enqueue all of them
61                 for (int j = 0; j < refs.length; j++) {
62                     refs[j].enqueue();
63                 }
64                 // and get them back. There should be exactly numReferences
65                 // entries in the queue now.
66                 int foundReferences = 0;
67                 while (queue.poll() != null) {
68                     foundReferences++;
69                 }
70 
71                 if (foundReferences != refs.length) {
72                     throw new RuntimeException("Got " + foundReferences + " references in the queue, but expected " + refs.length);
73                 }
74             }
75         }
76     }
77 }
78