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