TestDynShrinkHeap.java revision 8413:92457dfb91bd 
1/*
2 * Copyright (c) 2014, 2015, 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
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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 * @library /testlibrary
30 * @run main/othervm -XX:+UseAdaptiveSizePolicyWithSystemGC -XX:+UseParallelGC -XX:MinHeapFreeRatio=0 -XX:MaxHeapFreeRatio=100 -Xmx1g -verbose:gc TestDynShrinkHeap
31 */
32import jdk.test.lib.DynamicVMOption;
33import java.lang.management.ManagementFactory;
34import java.lang.management.MemoryUsage;
35import java.util.ArrayList;
36import static jdk.test.lib.Asserts.assertLessThan;
37import com.sun.management.HotSpotDiagnosticMXBean;
38
39public 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                ManagementFactory.getPlatformMXBean(HotSpotDiagnosticMXBean.class)
67                    .getVMOption(MIN_FREE_RATIO_FLAG_NAME).getValue(),
68                MAX_FREE_RATIO_FLAG_NAME,
69                ManagementFactory.getPlatformMXBean(HotSpotDiagnosticMXBean.class)
70                    .getVMOption(MAX_FREE_RATIO_FLAG_NAME).getValue()
71        ));
72    }
73
74    private void eat() {
75        for (int i = 0; i < LEN; i++) {
76            list.add(new byte[1024]);
77        }
78        MemoryUsagePrinter.printMemoryUsage("allocated " + LEN + " arrays");
79
80        list.subList(0, LEN / 2).clear();
81        System.gc();
82        MemoryUsagePrinter.printMemoryUsage("array halved");
83    }
84
85    private void free() {
86        int min = DynamicVMOption.getInt(MIN_FREE_RATIO_FLAG_NAME);
87        DynamicVMOption.setInt(MAX_FREE_RATIO_FLAG_NAME, min);
88        System.gc();
89        MemoryUsagePrinter.printMemoryUsage("under pressure");
90    }
91
92    public static void main(String[] args) {
93        new TestDynShrinkHeap().test();
94    }
95}
96
97/**
98 * Prints memory usage to standard output
99 */
100class MemoryUsagePrinter {
101
102    public static String humanReadableByteCount(long bytes, boolean si) {
103        int unit = si ? 1000 : 1024;
104        if (bytes < unit) {
105            return bytes + " B";
106        }
107        int exp = (int) (Math.log(bytes) / Math.log(unit));
108        String pre = (si ? "kMGTPE" : "KMGTPE").charAt(exp - 1) + (si ? "" : "i");
109        return String.format("%.1f %sB", bytes / Math.pow(unit, exp), pre);
110    }
111
112    public static void printMemoryUsage(String label) {
113        MemoryUsage memusage = ManagementFactory.getMemoryMXBean().getHeapMemoryUsage();
114        float freeratio = 1f - (float) memusage.getUsed() / memusage.getCommitted();
115        System.out.format("[%-24s] init: %-7s, used: %-7s, comm: %-7s, freeRatio ~= %.1f%%%n",
116                label,
117                humanReadableByteCount(memusage.getInit(), true),
118                humanReadableByteCount(memusage.getUsed(), true),
119                humanReadableByteCount(memusage.getCommitted(), true),
120                freeratio * 100
121        );
122    }
123}
124