1 /* 2 * Copyright (c) 2014, 2016, 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 * @requires vm.gc=="Parallel" | vm.gc=="null" 28 * @summary Verify that the heap shrinks after full GC according to the current values of the Min/MaxHeapFreeRatio flags 29 * @modules jdk.management 30 * @library /testlibrary 31 * @run main/othervm -XX:+UseAdaptiveSizePolicyWithSystemGC -XX:+UseParallelGC -XX:MinHeapFreeRatio=0 -XX:MaxHeapFreeRatio=100 -Xmx1g -verbose:gc TestDynShrinkHeap 32 */ 33 import jdk.test.lib.DynamicVMOption; 34 import java.lang.management.ManagementFactory; 35 import java.lang.management.MemoryUsage; 36 import java.util.ArrayList; 37 import static jdk.test.lib.Asserts.assertLessThan; 38 import com.sun.management.HotSpotDiagnosticMXBean; 39 40 public class TestDynShrinkHeap { 41 42 public static final String MIN_FREE_RATIO_FLAG_NAME = "MinHeapFreeRatio"; 43 public static final String MAX_FREE_RATIO_FLAG_NAME = "MaxHeapFreeRatio"; 44 45 private static ArrayList<byte[]> list = new ArrayList<>(0); 46 private static final int LEN = 512 * 1024 + 1; 47 48 public TestDynShrinkHeap() { 49 } 50 51 private final void test() { 52 System.gc(); 53 MemoryUsagePrinter.printMemoryUsage("init"); 54 55 eat(); 56 MemoryUsagePrinter.printMemoryUsage("eaten"); 57 MemoryUsage muFull = ManagementFactory.getMemoryMXBean().getHeapMemoryUsage(); 58 59 free(); 60 MemoryUsagePrinter.printMemoryUsage("free"); 61 MemoryUsage muFree = ManagementFactory.getMemoryMXBean().getHeapMemoryUsage(); 62 63 assertLessThan(muFree.getCommitted(), muFull.getCommitted(), String.format( 64 "committed free heap size is not less than committed full heap size, heap hasn't been shrunk?%n" 65 + "%s = %s%n%s = %s", 66 MIN_FREE_RATIO_FLAG_NAME, 67 ManagementFactory.getPlatformMXBean(HotSpotDiagnosticMXBean.class) 68 .getVMOption(MIN_FREE_RATIO_FLAG_NAME).getValue(), 69 MAX_FREE_RATIO_FLAG_NAME, 70 ManagementFactory.getPlatformMXBean(HotSpotDiagnosticMXBean.class) 71 .getVMOption(MAX_FREE_RATIO_FLAG_NAME).getValue() 72 )); 73 } 74 75 private void eat() { 76 for (int i = 0; i < LEN; i++) { 77 list.add(new byte[1024]); 78 } 79 MemoryUsagePrinter.printMemoryUsage("allocated " + LEN + " arrays"); 80 81 list.subList(0, LEN / 2).clear(); 82 System.gc(); 83 MemoryUsagePrinter.printMemoryUsage("array halved"); 84 } 85 86 private void free() { 87 int min = DynamicVMOption.getInt(MIN_FREE_RATIO_FLAG_NAME); 88 DynamicVMOption.setInt(MAX_FREE_RATIO_FLAG_NAME, min); 89 System.gc(); 90 MemoryUsagePrinter.printMemoryUsage("under pressure"); 91 } 92 93 public static void main(String[] args) { 94 new TestDynShrinkHeap().test(); 95 } 96 } 97 98 /** 99 * Prints memory usage to standard output 100 */ 101 class MemoryUsagePrinter { 102 103 public static String humanReadableByteCount(long bytes, boolean si) { 104 int unit = si ? 1000 : 1024; 105 if (bytes < unit) { 106 return bytes + " B"; 107 } 108 int exp = (int) (Math.log(bytes) / Math.log(unit)); 109 String pre = (si ? "kMGTPE" : "KMGTPE").charAt(exp - 1) + (si ? "" : "i"); 110 return String.format("%.1f %sB", bytes / Math.pow(unit, exp), pre); 111 } 112 113 public static void printMemoryUsage(String label) { 114 MemoryUsage memusage = ManagementFactory.getMemoryMXBean().getHeapMemoryUsage(); 115 float freeratio = 1f - (float) memusage.getUsed() / memusage.getCommitted(); 116 System.out.format("[%-24s] init: %-7s, used: %-7s, comm: %-7s, freeRatio ~= %.1f%%%n", 117 label, 118 humanReadableByteCount(memusage.getInit(), true), 119 humanReadableByteCount(memusage.getUsed(), true), 120 humanReadableByteCount(memusage.getCommitted(), true), 121 freeratio * 100 122 ); 123 } 124 }