1 /* 2 * Copyright (c) 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 TestNoEagerReclaimOfHumongousRegions 26 * @bug 8139424 27 * @summary Test to check that a live humongous object is not eagerly reclaimed. This is a regression test for 28 * 8139424 and the test will crash if an eager reclaim occur. The test is not 100% deterministic and 29 * might pass even if there are problems in the code, but it will never crash unless there is a problem. 30 * @requires vm.gc=="G1" | vm.gc=="null" 31 * @key gc 32 * @library /testlibrary /test/lib 33 * @modules java.base/sun.misc 34 * @build TestNoEagerReclaimOfHumongousRegions 35 * @run main ClassFileInstaller sun.hotspot.WhiteBox 36 * sun.hotspot.WhiteBox$WhiteBoxPermission 37 * @run main/othervm -Xbootclasspath/a:. -Xlog:gc,gc+humongous=debug -XX:+UseG1GC -XX:MaxTenuringThreshold=0 -XX:G1RSetSparseRegionEntries=32 -XX:G1HeapRegionSize=1m -XX:+UnlockDiagnosticVMOptions -XX:+WhiteBoxAPI TestNoEagerReclaimOfHumongousRegions 38 */ 39 40 import java.util.LinkedList; 41 42 import sun.hotspot.WhiteBox; 43 44 public class TestNoEagerReclaimOfHumongousRegions { 45 // Helper class to keep reference to humongous byte[]. 46 static class LargeRef { 47 private byte[] _ref; 48 49 LargeRef(byte[] ref) { 50 _ref = ref; 51 } 52 53 byte[] ref() { return _ref; } 54 } 55 56 static LargeRef humongous_reference_holder; 57 58 public static void main(String[] args) throws InterruptedException{ 59 WhiteBox wb = WhiteBox.getWhiteBox(); 60 LinkedList<Object> garbageAndRefList = new LinkedList<Object>(); 61 // Creating a 1M large byte array. Since the test specifies the heap 62 // region size to be 1m this will be a humongous object. We then 63 // store a pointer to the array in the static object to keep it live 64 // during the whole test. 65 humongous_reference_holder = new LargeRef(new byte[1 * 1024 * 1024]); 66 67 // Create some garbage and a reference to the humongous object each round. 68 for (int i = 0; i < 32; i++) { 69 garbageAndRefList.add(new byte[400*1000]); 70 garbageAndRefList.add(new LargeRef(humongous_reference_holder.ref())); 71 72 // Promote to old, goal is to get rem-set entries for the humongous 73 // object from different regions. The test specifies MaxTenuringThreshold=0, 74 // this will make sure we get objects promoted to old at once. 75 wb.youngGC(); 76 } 77 // Clear the garbage and reference list. 78 garbageAndRefList.clear(); 79 80 // Run a concurrent mark cycle to mark all references but the static one as dead. 81 wb.g1StartConcMarkCycle(); 82 while (wb.g1InConcurrentMark()) { 83 Thread.sleep(100); 84 } 85 86 // Run a young collection to make sure humongous object still can't be eagerly reclaimed. 87 wb.youngGC(); 88 // Will crash/assert if humongous object has been reclaimed. 89 wb.fullGC(); 90 } 91 }