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 8041506, 8041946, 8042051
26 * @test TestHumongousShrinkHeap
27 * @bug 8036025
28 * @summary Verify that heap shrinks after GC in the presence of fragmentation due to humongous objects
29 * @library /testlibrary
30 * @run main/othervm -XX:MinHeapFreeRatio=10 -XX:MaxHeapFreeRatio=50 -XX:+UseG1GC -XX:G1HeapRegionSize=1M -verbose:gc TestHumongousShrinkHeap
31 */
32
33 import java.lang.management.ManagementFactory;
34 import java.lang.management.MemoryUsage;
35 import java.util.ArrayList;
36 import java.util.List;
37 import sun.management.ManagementFactoryHelper;
38 import static com.oracle.java.testlibrary.Asserts.*;
39
40 public class TestHumongousShrinkHeap {
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 final ArrayList<ArrayList<byte[]>> garbage = new ArrayList<>();
46 private static final int PAGE_SIZE = 1024 * 1024; // 1M
47 private static final int PAGES_NUM = 5;
48
49
50 public static void main(String[] args) {
51 new TestHumongousShrinkHeap().test();
52 }
53
54 private final void test() {
55 System.gc();
56 MemoryUsagePrinter.printMemoryUsage("init");
57
58 eat();
59 MemoryUsagePrinter.printMemoryUsage("eaten");
60 MemoryUsage muFull = ManagementFactory.getMemoryMXBean().getHeapMemoryUsage();
61
62 free();
63 MemoryUsagePrinter.printMemoryUsage("free");
64 MemoryUsage muFree = ManagementFactory.getMemoryMXBean().getHeapMemoryUsage();
65
66 assertLessThan(muFree.getCommitted(), muFull.getCommitted(), String.format(
67 "committed free heap size is not less than committed full heap size, heap hasn't been shrunk?%n"
68 + "%s = %s%n%s = %s",
69 MIN_FREE_RATIO_FLAG_NAME,
70 ManagementFactoryHelper.getDiagnosticMXBean().getVMOption(MIN_FREE_RATIO_FLAG_NAME).getValue(),
71 MAX_FREE_RATIO_FLAG_NAME,
72 ManagementFactoryHelper.getDiagnosticMXBean().getVMOption(MAX_FREE_RATIO_FLAG_NAME).getValue()
73 ));
74 }
75
76 private void eat() {
77 int HumongousObjectSize = Math.round(.9f * PAGE_SIZE);
78 System.out.println("Will allocate objects of size=" +
79 MemoryUsagePrinter.humanReadableByteCount(HumongousObjectSize, true));
80
81 for (int i = 0; i < PAGES_NUM; i++) {
82 ArrayList<byte[]> stuff = new ArrayList<>();
83 eatList(stuff, 100, HumongousObjectSize);
84 MemoryUsagePrinter.printMemoryUsage("eat #" + i);
85 garbage.add(stuff);
86 }
87 }
88
89 private void free() {
90 // do not free last one list
91 garbage.subList(0, garbage.size() - 1).clear();
92
93 // do not free last one element from last list
94 ArrayList stuff = garbage.get(garbage.size() - 1);
95 stuff.subList(0, stuff.size() - 1).clear();
96 System.gc();
97 }
98
99 private static void eatList(List garbage, int count, int size) {
100 for (int i = 0; i < count; i++) {
101 garbage.add(new byte[size]);
102 }
103 }
104 }
105
106 /**
107 * Prints memory usage to standard output
108 */
109 class MemoryUsagePrinter {
110
111 public static String humanReadableByteCount(long bytes, boolean si) {
112 int unit = si ? 1000 : 1024;
113 if (bytes < unit) {
114 return bytes + " B";
115 }
116 int exp = (int) (Math.log(bytes) / Math.log(unit));
117 String pre = (si ? "kMGTPE" : "KMGTPE").charAt(exp - 1) + (si ? "" : "i");
118 return String.format("%.1f %sB", bytes / Math.pow(unit, exp), pre);
119 }
120
121 public static void printMemoryUsage(String label) {
122 MemoryUsage memusage = ManagementFactory.getMemoryMXBean().getHeapMemoryUsage();
123 float freeratio = 1f - (float) memusage.getUsed() / memusage.getCommitted();
124 System.out.format("[%-24s] init: %-7s, used: %-7s, comm: %-7s, freeRatio ~= %.1f%%%n",
125 label,
126 humanReadableByteCount(memusage.getInit(), true),
127 humanReadableByteCount(memusage.getUsed(), true),
128 humanReadableByteCount(memusage.getCommitted(), true),
129 freeratio * 100
130 );
131 }
132 }