1 /* 2 * Copyright (c) 2013, 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 8014890 26 * @summary Verify that a race between ReferenceQueue.enqueue() and poll() does not occur. 27 * @author thomas.schatzl@oracle.com 28 * @requires vm.gc=="Serial" | vm.gc=="null" 29 * @run main/othervm -XX:+UseSerialGC -Xmx10M EnqueuePollRace 30 */ 31 32 import java.lang.ref.*; 33 34 public class EnqueuePollRace { 35 36 public static void main(String args[]) throws Exception { 37 new WeakRef().run(); 38 System.out.println("Test passed."); 39 } 40 41 static class WeakRef { 42 ReferenceQueue<Object> queue = new ReferenceQueue<Object>(); 43 final int numReferences = 100; 44 final Reference refs[] = new Reference[numReferences]; 45 final int iterations = 1000; 46 47 void run() throws InterruptedException { 48 for (int i = 0; i < iterations; i++) { 49 queue = new ReferenceQueue<Object>(); 50 51 for (int j = 0; j < refs.length; j++) { 52 refs[j] = new WeakReference(new Object(), queue); 53 } 54 55 System.gc(); // enqueues references into the list of discovered references 56 57 // now manually enqueue all of them 58 for (int j = 0; j < refs.length; j++) { 59 refs[j].enqueue(); 60 } 61 // and get them back. There should be exactly numReferences 62 // entries in the queue now. 63 int foundReferences = 0; 64 while (queue.poll() != null) { 65 foundReferences++; 66 } 67 68 if (foundReferences != refs.length) { 69 throw new RuntimeException("Got " + foundReferences + " references in the queue, but expected " + refs.length); 70 } 71 } 72 } 73 } 74 }