TestDynShrinkHeap.java revision 11833:1cbffa2beba6 
1/*
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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
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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.
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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 */
34import jdk.test.lib.DynamicVMOption;
35import java.lang.management.ManagementFactory;
36import java.lang.management.MemoryUsage;
37import java.util.ArrayList;
38import static jdk.test.lib.Asserts.assertLessThan;
39import com.sun.management.HotSpotDiagnosticMXBean;
40
41public 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 */
102class 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}
126