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