1 /* 2 * Copyright (c) 2014, 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 TestShrinkDefragmentedHeap 26 * @bug 8038423 27 * @summary Verify that heap shrinks after GC in the presence of fragmentation due to humongous objects 28 * 1. allocate small objects mixed with humongous ones 29 * "ssssHssssHssssHssssHssssHssssHssssH" 30 * 2. release all allocated object except the last humongous one 31 * "..................................H" 32 * 3. invoke gc and check that memory returned to the system (amount of committed memory got down) 33 * 34 * @library /testlibrary 35 */ 36 import java.lang.management.ManagementFactory; 37 import java.lang.management.MemoryUsage; 38 import java.util.ArrayList; 39 import java.util.List; 40 import sun.management.ManagementFactoryHelper; 41 import static com.oracle.java.testlibrary.Asserts.*; 42 import com.oracle.java.testlibrary.ProcessTools; 43 import com.oracle.java.testlibrary.OutputAnalyzer; 44 45 public class TestShrinkDefragmentedHeap { 46 // Since we store all the small objects, they become old and old regions are also allocated at the bottom of the heap 47 // together with humongous regions. So if there are a lot of old regions in the lower part of the heap, 48 // the humongous regions will be allocated in the upper part of the heap anyway. 49 // To avoid this the Eden needs to be big enough to fit all the small objects. 50 private static final int INITIAL_HEAP_SIZE = 200 * 1024 * 1024; 51 private static final int MINIMAL_YOUNG_SIZE = 190 * 1024 * 1024; 52 private static final int REGION_SIZE = 1 * 1024 * 1024; 53 main(String[] args)54 public static void main(String[] args) throws Exception, Throwable { 55 ProcessBuilder pb = ProcessTools.createJavaProcessBuilder( 56 "-XX:InitialHeapSize=" + INITIAL_HEAP_SIZE, 57 "-Xmn" + MINIMAL_YOUNG_SIZE, 58 "-XX:MinHeapFreeRatio=10", 59 "-XX:MaxHeapFreeRatio=11", 60 "-XX:+UseG1GC", 61 "-XX:G1HeapRegionSize=" + REGION_SIZE, 62 "-XX:-ExplicitGCInvokesConcurrent", 63 "-verbose:gc", 64 GCTest.class.getName() 65 ); 66 67 OutputAnalyzer output = ProcessTools.executeProcess(pb); 68 output.shouldHaveExitValue(0); 69 } 70 71 static class GCTest { 72 73 private static final String MIN_FREE_RATIO_FLAG_NAME = "MinHeapFreeRatio"; 74 private static final String MAX_FREE_RATIO_FLAG_NAME = "MaxHeapFreeRatio"; 75 private static final String NEW_SIZE_FLAG_NAME = "NewSize"; 76 77 private static final ArrayList<ArrayList<byte[]>> garbage = new ArrayList<>(); 78 79 private static final int SMALL_OBJS_SIZE = 10 * 1024; // 10kB 80 private static final int SMALL_OBJS_COUNT = MINIMAL_YOUNG_SIZE / (SMALL_OBJS_SIZE-1); 81 private static final int ALLOCATE_COUNT = 3; 82 // try to put all humongous object into gap between min young size and initial heap size 83 // to avoid implicit GCs 84 private static final int HUMONG_OBJS_SIZE = (int) Math.max( 85 (INITIAL_HEAP_SIZE - MINIMAL_YOUNG_SIZE) / ALLOCATE_COUNT / 4, 86 REGION_SIZE * 1.1 87 ); 88 89 private static final long initialHeapSize = getHeapMemoryUsage().getUsed(); 90 main(String[] args)91 public static void main(String[] args) throws InterruptedException { 92 new GCTest().test(); 93 } 94 test()95 private void test() throws InterruptedException { 96 MemoryUsagePrinter.printMemoryUsage("init"); 97 98 allocate(); 99 System.gc(); 100 MemoryUsage muFull = getHeapMemoryUsage(); 101 MemoryUsagePrinter.printMemoryUsage("allocated"); 102 103 free(); 104 //Thread.sleep(1000); // sleep before measures due lags in JMX 105 MemoryUsage muFree = getHeapMemoryUsage(); 106 MemoryUsagePrinter.printMemoryUsage("free"); 107 108 assertLessThan(muFree.getCommitted(), muFull.getCommitted(), prepareMessageCommittedIsNotLess() ); 109 } 110 allocate()111 private void allocate() { 112 System.out.format("Will allocate objects of small size = %s and humongous size = %s", 113 MemoryUsagePrinter.humanReadableByteCount(SMALL_OBJS_SIZE, false), 114 MemoryUsagePrinter.humanReadableByteCount(HUMONG_OBJS_SIZE, false) 115 ); 116 117 for (int i = 0; i < ALLOCATE_COUNT; i++) { 118 ArrayList<byte[]> stuff = new ArrayList<>(); 119 allocateList(stuff, SMALL_OBJS_COUNT / ALLOCATE_COUNT, SMALL_OBJS_SIZE); 120 garbage.add(stuff); 121 122 ArrayList<byte[]> humongousStuff = new ArrayList<>(); 123 allocateList(humongousStuff, 4, HUMONG_OBJS_SIZE); 124 garbage.add(humongousStuff); 125 } 126 } 127 free()128 private void free() { 129 // do not free last one list 130 garbage.subList(0, garbage.size() - 1).clear(); 131 132 // do not free last one element from last list 133 ArrayList stuff = garbage.get(garbage.size() - 1); 134 if (stuff.size() > 1) { 135 stuff.subList(0, stuff.size() - 1).clear(); 136 } 137 System.gc(); 138 } 139 prepareMessageCommittedIsNotLess()140 private String prepareMessageCommittedIsNotLess() { 141 return String.format( 142 "committed free heap size is not less than committed full heap size, heap hasn't been shrunk?%n" 143 + "%s = %s%n%s = %s", 144 MIN_FREE_RATIO_FLAG_NAME, 145 ManagementFactoryHelper.getDiagnosticMXBean().getVMOption(MIN_FREE_RATIO_FLAG_NAME).getValue(), 146 MAX_FREE_RATIO_FLAG_NAME, 147 ManagementFactoryHelper.getDiagnosticMXBean().getVMOption(MAX_FREE_RATIO_FLAG_NAME).getValue() 148 ); 149 } 150 allocateList(List garbage, int count, int size)151 private static void allocateList(List garbage, int count, int size) { 152 for (int i = 0; i < count; i++) { 153 garbage.add(new byte[size]); 154 } 155 } 156 } 157 getHeapMemoryUsage()158 static MemoryUsage getHeapMemoryUsage() { 159 return ManagementFactory.getMemoryMXBean().getHeapMemoryUsage(); 160 } 161 162 /** 163 * Prints memory usage to standard output 164 */ 165 static class MemoryUsagePrinter { 166 humanReadableByteCount(long bytes, boolean si)167 public static String humanReadableByteCount(long bytes, boolean si) { 168 int unit = si ? 1000 : 1024; 169 if (bytes < unit) { 170 return bytes + " B"; 171 } 172 int exp = (int) (Math.log(bytes) / Math.log(unit)); 173 String pre = (si ? "kMGTPE" : "KMGTPE").charAt(exp - 1) + (si ? "" : "i"); 174 return String.format("%.1f %sB", bytes / Math.pow(unit, exp), pre); 175 } 176 printMemoryUsage(String label)177 public static void printMemoryUsage(String label) { 178 MemoryUsage memusage = ManagementFactory.getMemoryMXBean().getHeapMemoryUsage(); 179 float freeratio = 1f - (float) memusage.getUsed() / memusage.getCommitted(); 180 System.out.format("[%-24s] init: %-7s, used: %-7s, comm: %-7s, freeRatio ~= %.1f%%%n", 181 label, 182 humanReadableByteCount(memusage.getInit(), false), 183 humanReadableByteCount(memusage.getUsed(), false), 184 humanReadableByteCount(memusage.getCommitted(), false), 185 freeratio * 100 186 ); 187 } 188 } 189 } 190