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 * @requires vm.gc=="Parallel" | vm.gc=="null" 29 * @summary Verify that the heap shrinks after full GC according to the current values of the Min/MaxHeapFreeRatio flags 30 * @library /testlibrary 31 * @run main/othervm -XX:+UseAdaptiveSizePolicyWithSystemGC -XX:+UseParallelGC -XX:MinHeapFreeRatio=0 -XX:MaxHeapFreeRatio=100 -Xmx1g -verbose:gc TestDynShrinkHeap 32 */ 33 import com.oracle.java.testlibrary.DynamicVMOption; 34 import java.lang.management.ManagementFactory; 35 import java.lang.management.MemoryUsage; 36 import java.util.ArrayList; 37 import sun.management.ManagementFactoryHelper; 38 import static com.oracle.java.testlibrary.Asserts.*; 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 ManagementFactoryHelper.getDiagnosticMXBean().getVMOption(MIN_FREE_RATIO_FLAG_NAME).getValue(), 68 MAX_FREE_RATIO_FLAG_NAME, 69 ManagementFactoryHelper.getDiagnosticMXBean().getVMOption(MAX_FREE_RATIO_FLAG_NAME).getValue() 70 )); 71 } 72 73 private void eat() { 74 for (int i = 0; i < LEN; i++) { 75 list.add(new byte[1024]); 76 } 77 MemoryUsagePrinter.printMemoryUsage("allocated " + LEN + " arrays"); 78 79 list.subList(0, LEN / 2).clear(); 80 System.gc(); 81 MemoryUsagePrinter.printMemoryUsage("array halved"); 82 } 83 84 private void free() { 85 int min = DynamicVMOption.getInt(MIN_FREE_RATIO_FLAG_NAME); 86 DynamicVMOption.setInt(MAX_FREE_RATIO_FLAG_NAME, min); 87 System.gc(); 88 MemoryUsagePrinter.printMemoryUsage("under pressure"); 89 } 90 91 public static void main(String[] args) { 92 new TestDynShrinkHeap().test(); 93 } 94 } 95 96 /** 97 * Prints memory usage to standard output 98 */ 99 class MemoryUsagePrinter { 100 101 public static String humanReadableByteCount(long bytes, boolean si) { 102 int unit = si ? 1000 : 1024; 103 if (bytes < unit) { 104 return bytes + " B"; 105 } 106 int exp = (int) (Math.log(bytes) / Math.log(unit)); 107 String pre = (si ? "kMGTPE" : "KMGTPE").charAt(exp - 1) + (si ? "" : "i"); 108 return String.format("%.1f %sB", bytes / Math.pow(unit, exp), pre); 109 } 110 111 public static void printMemoryUsage(String label) { 112 MemoryUsage memusage = ManagementFactory.getMemoryMXBean().getHeapMemoryUsage(); 113 float freeratio = 1f - (float) memusage.getUsed() / memusage.getCommitted(); 114 System.out.format("[%-24s] init: %-7s, used: %-7s, comm: %-7s, freeRatio ~= %.1f%%%n", 115 label, 116 humanReadableByteCount(memusage.getInit(), true), 117 humanReadableByteCount(memusage.getUsed(), true), 118 humanReadableByteCount(memusage.getCommitted(), true), 119 freeratio * 100 120 ); 121 } 122 }