1 /* 2 * Copyright (c) 2020, Red Hat, Inc. 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 /* 26 * @test TestWeakReferenceChurn 27 * @summary Check that -XX:+ShenandoahAggressiveReferenceDiscovery reclaims references 28 * even when accessed during marking 29 * @key gc 30 * @requires vm.gc.Shenandoah & !vm.graal.enabled 31 * 32 * @run main/othervm -XX:+UnlockDiagnosticVMOptions -XX:+UnlockExperimentalVMOptions -Xmx1g -Xms1g 33 * -XX:+UseShenandoahGC -XX:ShenandoahGuaranteedGCInterval=1 34 * -XX:+ShenandoahAggressiveReferenceDiscovery 35 * TestWeakReferenceChurn 36 */ 37 38 import java.lang.ref.WeakReference; 39 import java.util.ArrayList; 40 import java.util.Random; 41 42 public class TestWeakReferenceChurn { 43 44 public static final int NUM_REFS = 1000000; 45 public static final int NUM_ITERS = 1000; 46 public static class Payload { 47 public int foo; 48 public Payload() { 49 foo = 0; 50 } 51 } 52 53 private static ArrayList<WeakReference<Payload>> refs; 54 private static Random random; 55 56 public static void main(String[] args) { 57 refs = new ArrayList<>(NUM_REFS); 58 random = new Random(); 59 for (int i = 0; i < NUM_REFS; i++) { 60 refs.add(new WeakReference(new Payload())); 61 } 62 int count = 0; 63 for (int j = 0; j < NUM_ITERS; j++) { 64 count = 0; 65 for (int i = 0; i < NUM_REFS; i++) { 66 if (accessRef(i)) { 67 count++; 68 } 69 } 70 if (count == 0) { 71 break; 72 } 73 } 74 if (count != 0) { 75 throw new RuntimeException("References not reclaimed"); 76 } 77 } 78 79 private static boolean accessRef(int idx) { 80 Payload item = refs.get(idx).get(); 81 if (item != null) { 82 item.foo = random.nextInt(); 83 return true; 84 } else { 85 return false; 86 } 87 } 88 }