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 * @ignore 8019361 26 * @test TestDynShrinkHeap 27 * @bug 8016479 28 * @summary Verify that the heap shrinks after full GC according to the current values of the Min/MaxHeapFreeRatio flags 29 * @library /testlibrary 30 * @run main/othervm -XX:+UseAdaptiveSizePolicyWithSystemGC -XX:+UseParallelGC -XX:MinHeapFreeRatio=0 -XX:MaxHeapFreeRatio=100 -Xmx1g -verbose:gc TestDynShrinkHeap 31 */ 32 import com.oracle.java.testlibrary.DynamicVMOption; 33 import java.lang.management.ManagementFactory; 34 import java.lang.management.MemoryUsage; 35 import java.util.ArrayList; 36 import sun.management.ManagementFactoryHelper; 37 import static com.oracle.java.testlibrary.Asserts.*; 38 39 public class TestDynShrinkHeap { 40 41 public static final String MIN_FREE_RATIO_FLAG_NAME = "MinHeapFreeRatio"; 42 public static final String MAX_FREE_RATIO_FLAG_NAME = "MaxHeapFreeRatio"; 43 44 private static ArrayList<byte[]> list = new ArrayList<>(0); 45 private static final int LEN = 512 * 1024 + 1; 46 47 public TestDynShrinkHeap() { 48 } 49 50 private final void test() { 51 System.gc(); 52 MemoryUsagePrinter.printMemoryUsage("init"); 53 54 eat(); 55 MemoryUsagePrinter.printMemoryUsage("eaten"); 56 MemoryUsage muFull = ManagementFactory.getMemoryMXBean().getHeapMemoryUsage(); 57 58 free(); 59 MemoryUsagePrinter.printMemoryUsage("free"); 60 MemoryUsage muFree = ManagementFactory.getMemoryMXBean().getHeapMemoryUsage(); 61 62 assertLessThan(muFree.getCommitted(), muFull.getCommitted(), String.format( 63 "committed free heap size is not less than committed full heap size, heap hasn't been shrunk?%n" 64 + "%s = %s%n%s = %s", 65 MIN_FREE_RATIO_FLAG_NAME, 66 ManagementFactoryHelper.getDiagnosticMXBean().getVMOption(MIN_FREE_RATIO_FLAG_NAME).getValue(), 67 MAX_FREE_RATIO_FLAG_NAME, 68 ManagementFactoryHelper.getDiagnosticMXBean().getVMOption(MAX_FREE_RATIO_FLAG_NAME).getValue() 69 )); 70 } 71 72 private void eat() { 73 for (int i = 0; i < LEN; i++) { 74 list.add(new byte[1024]); 75 } 76 MemoryUsagePrinter.printMemoryUsage("allocated " + LEN + " arrays"); 77 78 list.subList(0, LEN / 2).clear(); 79 System.gc(); 80 MemoryUsagePrinter.printMemoryUsage("array halved"); 81 } 82 83 private void free() { 84 int min = DynamicVMOption.getInt(MIN_FREE_RATIO_FLAG_NAME); 85 DynamicVMOption.setInt(MAX_FREE_RATIO_FLAG_NAME, min); 86 System.gc(); 87 MemoryUsagePrinter.printMemoryUsage("under pressure"); 88 } 89 90 public static void main(String[] args) { 91 new TestDynShrinkHeap().test(); 92 } 93 } 94 95 /** 96 * Prints memory usage to standard output 97 */ 98 class MemoryUsagePrinter { 99 100 public static String humanReadableByteCount(long bytes, boolean si) { 101 int unit = si ? 1000 : 1024; 102 if (bytes < unit) { 103 return bytes + " B"; 104 } 105 int exp = (int) (Math.log(bytes) / Math.log(unit)); 106 String pre = (si ? "kMGTPE" : "KMGTPE").charAt(exp - 1) + (si ? "" : "i"); 107 return String.format("%.1f %sB", bytes / Math.pow(unit, exp), pre); 108 } 109 110 public static void printMemoryUsage(String label) { 111 MemoryUsage memusage = ManagementFactory.getMemoryMXBean().getHeapMemoryUsage(); 112 float freeratio = 1f - (float) memusage.getUsed() / memusage.getCommitted(); 113 System.out.format("[%-24s] init: %-7s, used: %-7s, comm: %-7s, freeRatio ~= %.1f%%%n", 114 label, 115 humanReadableByteCount(memusage.getInit(), true), 116 humanReadableByteCount(memusage.getUsed(), true), 117 humanReadableByteCount(memusage.getCommitted(), true), 118 freeratio * 100 119 ); 120 } 121 }