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 * @test TestHumongousShrinkHeap
26 * @bug 8036025 8056043
27 * @requires vm.gc=="G1" | vm.gc=="null"
28 * @summary Verify that heap shrinks after GC in the presence of fragmentation
29 * due to humongous objects
30 * @library /testlibrary
31 * @run main/othervm -XX:-ExplicitGCInvokesConcurrent -XX:MinHeapFreeRatio=10
32 * -XX:MaxHeapFreeRatio=12 -XX:+UseG1GC -XX:G1HeapRegionSize=1M -verbose:gc
33 * TestHumongousShrinkHeap
34 */
35
36 import java.lang.management.ManagementFactory;
37 import java.lang.management.MemoryUsage;
38 import java.util.ArrayList;
39 import java.util.List;
40 import sun.management.ManagementFactoryHelper;
41 import static com.oracle.java.testlibrary.Asserts.*;
42
43 public class TestHumongousShrinkHeap {
44
45 public static final String MIN_FREE_RATIO_FLAG_NAME = "MinHeapFreeRatio";
46 public static final String MAX_FREE_RATIO_FLAG_NAME = "MaxHeapFreeRatio";
47
48 private static final List<List<byte[]>> garbage = new ArrayList();
49 private static final int REGION_SIZE = 1024 * 1024; // 1M
50 private static final int LISTS_COUNT = 10;
51 private static final int HUMON_SIZE = Math.round(.9f * REGION_SIZE);
52 private static final long AVAILABLE_MEMORY
53 = Runtime.getRuntime().freeMemory();
54 private static final int HUMON_COUNT
55 = (int) ((AVAILABLE_MEMORY / HUMON_SIZE)
56 / LISTS_COUNT);
57
58
59 public static void main(String[] args) {
60 System.out.format("Running with %s max heap size. "
61 + "Will allocate humongous object of %s size %d times.%n",
62 MemoryUsagePrinter.humanReadableByteCount(AVAILABLE_MEMORY, false),
63 MemoryUsagePrinter.humanReadableByteCount(HUMON_SIZE, false),
64 HUMON_COUNT
65 );
66 new TestHumongousShrinkHeap().test();
67 }
68
69 private final void test() {
70 System.gc();
71 MemoryUsagePrinter.printMemoryUsage("init");
72
73 allocate();
74 MemoryUsagePrinter.printMemoryUsage("allocated");
75 MemoryUsage muFull = ManagementFactory.getMemoryMXBean().getHeapMemoryUsage();
76
77 free();
78 MemoryUsagePrinter.printMemoryUsage("free");
79 MemoryUsage muFree = ManagementFactory.getMemoryMXBean().getHeapMemoryUsage();
80
81 assertLessThan(muFree.getCommitted(), muFull.getCommitted(), String.format(
82 "committed free heap size is not less than committed full heap size, heap hasn't been shrunk?%n"
83 + "%s = %s%n%s = %s",
84 MIN_FREE_RATIO_FLAG_NAME,
85 ManagementFactoryHelper.getDiagnosticMXBean().getVMOption(MIN_FREE_RATIO_FLAG_NAME).getValue(),
86 MAX_FREE_RATIO_FLAG_NAME,
87 ManagementFactoryHelper.getDiagnosticMXBean().getVMOption(MAX_FREE_RATIO_FLAG_NAME).getValue()
88 ));
89 }
90
91 private void allocate() {
92
93 for (int i = 0; i < LISTS_COUNT; i++) {
94 List<byte[]> stuff = new ArrayList();
95 allocateList(stuff, HUMON_COUNT, HUMON_SIZE);
96 MemoryUsagePrinter.printMemoryUsage("allocate #" + (i+1));
97 garbage.add(stuff);
98 }
99 }
100
101 private void free() {
102 // do not free last one list
103 garbage.subList(0, garbage.size() - 1).clear();
104
105 // do not free last one element from last list
106 List stuff = garbage.get(garbage.size() - 1);
107 stuff.subList(0, stuff.size() - 1).clear();
108 System.gc();
109 }
110
111 private static void allocateList(List garbage, int count, int size) {
112 for (int i = 0; i < count; i++) {
113 garbage.add(new byte[size]);
114 }
115 }
116 }
117
118 /**
119 * Prints memory usage to standard output
120 */
121 class MemoryUsagePrinter {
122
123 public static String humanReadableByteCount(long bytes, boolean si) {
124 int unit = si ? 1000 : 1024;
125 if (bytes < unit) {
126 return bytes + " B";
127 }
128 int exp = (int) (Math.log(bytes) / Math.log(unit));
129 String pre = (si ? "kMGTPE" : "KMGTPE").charAt(exp - 1) + (si ? "" : "i");
130 return String.format("%.1f %sB", bytes / Math.pow(unit, exp), pre);
131 }
132
133 public static void printMemoryUsage(String label) {
134 MemoryUsage memusage = ManagementFactory.getMemoryMXBean().getHeapMemoryUsage();
135 float freeratio = 1f - (float) memusage.getUsed() / memusage.getCommitted();
136 System.out.format("[%-24s] init: %-7s, used: %-7s, comm: %-7s, freeRatio ~= %.1f%%%n",
137 label,
138 humanReadableByteCount(memusage.getInit(), false),
139 humanReadableByteCount(memusage.getUsed(), false),
140 humanReadableByteCount(memusage.getCommitted(), false),
141 freeratio * 100
142 );
143 }
144 }