1 /* 2 * Copyright (c) 2014, 2015, 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 * @library /testlibrary 34 * @modules java.base/sun.misc 35 * java.management 36 */ 37 38 import java.util.regex.Pattern; 39 import java.util.regex.Matcher; 40 import java.util.LinkedList; 41 42 import jdk.test.lib.OutputAnalyzer; 43 import jdk.test.lib.ProcessTools; 44 import static jdk.test.lib.Asserts.*; 45 46 class RefHolder { 47 Object ref; 48 } 49 50 class ReclaimRegionFast { 51 52 public static final int M = 1024*1024; 53 54 public static LinkedList<Object> garbageList = new LinkedList<Object>(); 55 56 public static void genGarbage() { 57 for (int i = 0; i < 32*1024; i++) { 58 garbageList.add(new int[100]); 59 } 60 garbageList.clear(); 61 } 62 63 64 // A large object referenced by a static. 65 static int[] filler = new int[10 * M]; 66 67 // Old gen object referencing the large object, generating remembered 68 // set entries. 69 static RefHolder fromOld = new RefHolder(); 70 71 public static void main(String[] args) { 72 73 int[] large = new int[M]; 74 75 Object ref_from_stack = large; 76 77 for (int i = 0; i < 100; i++) { 78 // A large object that will be reclaimed eagerly. 79 large = new int[6*M]; 80 fromOld.ref = large; 81 genGarbage(); 82 } 83 84 // Keep the reference to the first object alive. 85 System.out.println(ref_from_stack); 86 } 87 } 88 89 public class TestEagerReclaimHumongousRegionsWithRefs { 90 91 public static void main(String[] args) throws Exception { 92 ProcessBuilder pb = ProcessTools.createJavaProcessBuilder( 93 "-XX:+UseG1GC", 94 "-Xms128M", 95 "-Xmx128M", 96 "-Xmn16M", 97 "-Xlog:gc", 98 ReclaimRegionFast.class.getName()); 99 100 Pattern p = Pattern.compile("Full GC"); 101 102 OutputAnalyzer output = new OutputAnalyzer(pb.start()); 103 104 int found = 0; 105 Matcher m = p.matcher(output.getStdout()); 106 while (m.find()) { 107 found++; 108 } 109 System.out.println("Issued " + found + " Full GCs"); 110 111 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"); 112 output.shouldHaveExitValue(0); 113 } 114 } 115