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
28 * @summary Verify that the heap shrinks after full GC according to the current values of the Min/MaxHeapFreeRatio flags
29 * @modules java.base/jdk.internal.misc
30 * @modules jdk.management
31 * @library /test/lib
32 * @run main/othervm -XX:+UseAdaptiveSizePolicyWithSystemGC -XX:+UseParallelGC -XX:MinHeapFreeRatio=0 -XX:MaxHeapFreeRatio=100 -Xmx1g -verbose:gc TestDynShrinkHeap
33 */
34 import jdk.test.lib.DynamicVMOption;
35 import java.lang.management.ManagementFactory;
36 import java.lang.management.MemoryUsage;
37 import java.util.ArrayList;
38 import static jdk.test.lib.Asserts.assertLessThan;
39 import com.sun.management.HotSpotDiagnosticMXBean;
40
41 public class TestDynShrinkHeap {
42
43 public static final String MIN_FREE_RATIO_FLAG_NAME = "MinHeapFreeRatio";
44 public static final String MAX_FREE_RATIO_FLAG_NAME = "MaxHeapFreeRatio";
45
46 private static ArrayList<byte[]> list = new ArrayList<>(0);
47 private static final int LEN = 512 * 1024 + 1;
48
49 public TestDynShrinkHeap() {
50 }
51
52 private final void test() {
53 System.gc();
54 MemoryUsagePrinter.printMemoryUsage("init");
55
56 eat();
57 MemoryUsagePrinter.printMemoryUsage("eaten");
58 MemoryUsage muFull = ManagementFactory.getMemoryMXBean().getHeapMemoryUsage();
59
60 free();
61 MemoryUsagePrinter.printMemoryUsage("free");
62 MemoryUsage muFree = ManagementFactory.getMemoryMXBean().getHeapMemoryUsage();
63
64 assertLessThan(muFree.getCommitted(), muFull.getCommitted(), String.format(
65 "committed free heap size is not less than committed full heap size, heap hasn't been shrunk?%n"
66 + "%s = %s%n%s = %s",
67 MIN_FREE_RATIO_FLAG_NAME,
68 ManagementFactory.getPlatformMXBean(HotSpotDiagnosticMXBean.class)
69 .getVMOption(MIN_FREE_RATIO_FLAG_NAME).getValue(),
70 MAX_FREE_RATIO_FLAG_NAME,
71 ManagementFactory.getPlatformMXBean(HotSpotDiagnosticMXBean.class)
72 .getVMOption(MAX_FREE_RATIO_FLAG_NAME).getValue()
73 ));
74 }
75
76 private void eat() {
77 for (int i = 0; i < LEN; i++) {
78 list.add(new byte[1024]);
79 }
80 MemoryUsagePrinter.printMemoryUsage("allocated " + LEN + " arrays");
81
82 list.subList(0, LEN / 2).clear();
83 System.gc();
84 MemoryUsagePrinter.printMemoryUsage("array halved");
85 }
86
87 private void free() {
88 int min = DynamicVMOption.getInt(MIN_FREE_RATIO_FLAG_NAME);
89 DynamicVMOption.setInt(MAX_FREE_RATIO_FLAG_NAME, min);
90 System.gc();
91 MemoryUsagePrinter.printMemoryUsage("under pressure");
92 }
93
94 public static void main(String[] args) {
95 new TestDynShrinkHeap().test();
96 }
97 }
98
99 /**
100 * Prints memory usage to standard output
101 */
102 class MemoryUsagePrinter {
103
104 public static String humanReadableByteCount(long bytes, boolean si) {
105 int unit = si ? 1000 : 1024;
106 if (bytes < unit) {
107 return bytes + " B";
108 }
109 int exp = (int) (Math.log(bytes) / Math.log(unit));
110 String pre = (si ? "kMGTPE" : "KMGTPE").charAt(exp - 1) + (si ? "" : "i");
111 return String.format("%.1f %sB", bytes / Math.pow(unit, exp), pre);
112 }
113
114 public static void printMemoryUsage(String label) {
115 MemoryUsage memusage = ManagementFactory.getMemoryMXBean().getHeapMemoryUsage();
116 float freeratio = 1f - (float) memusage.getUsed() / memusage.getCommitted();
117 System.out.format("[%-24s] init: %-7s, used: %-7s, comm: %-7s, freeRatio ~= %.1f%%%n",
118 label,
119 humanReadableByteCount(memusage.getInit(), true),
120 humanReadableByteCount(memusage.getUsed(), true),
121 humanReadableByteCount(memusage.getCommitted(), true),
122 freeratio * 100
123 );
124 }
125 }