1 /* 2 * Copyright (c) 2014, 2016, 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 TestEagerReclaimHumongousRegionsWithRefs 26 * @bug 8048179 27 * @summary Test to make sure that eager reclaim of humongous objects that have previously 28 * been referenced by other old gen regions work. We simply try to fill 29 * up the heap with humongous objects and create a remembered set entry from an object by 30 * referencing that we know is in the old gen. After changing this reference, the object 31 * should still be eagerly reclaimable to avoid Full GC. 32 * @key gc 33 * @requires vm.gc.G1 34 * @library /test/lib 35 * @modules java.base/jdk.internal.misc 36 * java.management 37 */ 38 39 import java.util.regex.Pattern; 40 import java.util.regex.Matcher; 41 import java.util.LinkedList; 42 43 import jdk.test.lib.process.OutputAnalyzer; 44 import jdk.test.lib.process.ProcessTools; 45 import static jdk.test.lib.Asserts.*; 46 47 class RefHolder { 48 Object ref; 49 } 50 51 class ReclaimRegionFast { 52 53 public static final int M = 1024*1024; 54 55 public static LinkedList<Object> garbageList = new LinkedList<Object>(); 56 57 public static void genGarbage() { 58 for (int i = 0; i < 32*1024; i++) { 59 garbageList.add(new int[100]); 60 } 61 garbageList.clear(); 62 } 63 64 65 // A large object referenced by a static. 66 static int[] filler = new int[10 * M]; 67 68 // Old gen object referencing the large object, generating remembered 69 // set entries. 70 static RefHolder fromOld = new RefHolder(); 71 72 public static void main(String[] args) { 73 74 int[] large = new int[M]; 75 76 Object ref_from_stack = large; 77 78 for (int i = 0; i < 100; i++) { 79 // A large object that will be reclaimed eagerly. 80 large = new int[6*M]; 81 fromOld.ref = large; 82 genGarbage(); 83 } 84 85 // Keep the reference to the first object alive. 86 System.out.println(ref_from_stack); 87 } 88 } 89 90 public class TestEagerReclaimHumongousRegionsWithRefs { 91 92 public static void main(String[] args) throws Exception { 93 ProcessBuilder pb = ProcessTools.createJavaProcessBuilder( 94 "-XX:+UseG1GC", 95 "-Xms128M", 96 "-Xmx128M", 97 "-Xmn16M", 98 "-Xlog:gc", 99 ReclaimRegionFast.class.getName()); 100 101 Pattern p = Pattern.compile("Full GC"); 102 103 OutputAnalyzer output = new OutputAnalyzer(pb.start()); 104 105 int found = 0; 106 Matcher m = p.matcher(output.getStdout()); 107 while (m.find()) { 108 found++; 109 } 110 System.out.println("Issued " + found + " Full GCs"); 111 112 assertLessThan(found, 10, "Found that " + found + " Full GCs were issued. This is larger than the bound. Eager reclaim of objects once referenced from old gen seems to not work at all"); 113 output.shouldHaveExitValue(0); 114 } 115 } 116