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 * @build com.oracle.java.testlibrary.*
32 * @run main/othervm -XX:-ExplicitGCInvokesConcurrent -XX:MinHeapFreeRatio=10
33 * -XX:MaxHeapFreeRatio=12 -XX:+UseG1GC -XX:G1HeapRegionSize=1M -verbose:gc
34 * TestHumongousShrinkHeap
35 */
36
37 import java.lang.management.ManagementFactory;
38 import java.lang.management.MemoryUsage;
39 import java.util.ArrayList;
40 import java.util.List;
41 import sun.management.ManagementFactoryHelper;
42 import static com.oracle.java.testlibrary.Asserts.*;
43
44 public class TestHumongousShrinkHeap {
45
46 public static final String MIN_FREE_RATIO_FLAG_NAME = "MinHeapFreeRatio";
47 public static final String MAX_FREE_RATIO_FLAG_NAME = "MaxHeapFreeRatio";
48
49 private static final List<List<byte[]>> garbage = new ArrayList();
50 private static final int REGION_SIZE = 1024 * 1024; // 1M
51 private static final int LISTS_COUNT = 10;
52 private static final int HUMON_SIZE = Math.round(.9f * REGION_SIZE);
53 private static final long AVAILABLE_MEMORY
54 = Runtime.getRuntime().freeMemory();
55 private static final int HUMON_COUNT
56 = (int) ((AVAILABLE_MEMORY / HUMON_SIZE)
57 / LISTS_COUNT);
58
59
60 public static void main(String[] args) {
61 System.out.format("Running with %s max heap size. "
62 + "Will allocate humongous object of %s size %d times.%n",
63 MemoryUsagePrinter.humanReadableByteCount(AVAILABLE_MEMORY, false),
64 MemoryUsagePrinter.humanReadableByteCount(HUMON_SIZE, false),
65 HUMON_COUNT
66 );
67 new TestHumongousShrinkHeap().test();
68 }
69
70 private final void test() {
71 System.gc();
72 MemoryUsagePrinter.printMemoryUsage("init");
73
74 allocate();
75 MemoryUsagePrinter.printMemoryUsage("allocated");
76 MemoryUsage muFull = ManagementFactory.getMemoryMXBean().getHeapMemoryUsage();
77
78 free();
79 MemoryUsagePrinter.printMemoryUsage("free");
80 MemoryUsage muFree = ManagementFactory.getMemoryMXBean().getHeapMemoryUsage();
81
82 assertLessThan(muFree.getCommitted(), muFull.getCommitted(), String.format(
83 "committed free heap size is not less than committed full heap size, heap hasn't been shrunk?%n"
84 + "%s = %s%n%s = %s",
85 MIN_FREE_RATIO_FLAG_NAME,
86 ManagementFactoryHelper.getDiagnosticMXBean().getVMOption(MIN_FREE_RATIO_FLAG_NAME).getValue(),
87 MAX_FREE_RATIO_FLAG_NAME,
88 ManagementFactoryHelper.getDiagnosticMXBean().getVMOption(MAX_FREE_RATIO_FLAG_NAME).getValue()
89 ));
90 }
91
92 private void allocate() {
93
94 for (int i = 0; i < LISTS_COUNT; i++) {
95 List<byte[]> stuff = new ArrayList();
96 allocateList(stuff, HUMON_COUNT, HUMON_SIZE);
97 MemoryUsagePrinter.printMemoryUsage("allocate #" + (i+1));
98 garbage.add(stuff);
99 }
100 }
101
102 private void free() {
103 // do not free last one list
104 garbage.subList(0, garbage.size() - 1).clear();
105
106 // do not free last one element from last list
107 List stuff = garbage.get(garbage.size() - 1);
108 stuff.subList(0, stuff.size() - 1).clear();
109 System.gc();
110 }
111
112 private static void allocateList(List garbage, int count, int size) {
113 for (int i = 0; i < count; i++) {
114 garbage.add(new byte[size]);
115 }
116 }
117 }
118
119 /**
120 * Prints memory usage to standard output
121 */
122 class MemoryUsagePrinter {
123
124 public static String humanReadableByteCount(long bytes, boolean si) {
125 int unit = si ? 1000 : 1024;
126 if (bytes < unit) {
127 return bytes + " B";
128 }
129 int exp = (int) (Math.log(bytes) / Math.log(unit));
130 String pre = (si ? "kMGTPE" : "KMGTPE").charAt(exp - 1) + (si ? "" : "i");
131 return String.format("%.1f %sB", bytes / Math.pow(unit, exp), pre);
132 }
133
134 public static void printMemoryUsage(String label) {
135 MemoryUsage memusage = ManagementFactory.getMemoryMXBean().getHeapMemoryUsage();
136 float freeratio = 1f - (float) memusage.getUsed() / memusage.getCommitted();
137 System.out.format("[%-24s] init: %-7s, used: %-7s, comm: %-7s, freeRatio ~= %.1f%%%n",
138 label,
139 humanReadableByteCount(memusage.getInit(), false),
140 humanReadableByteCount(memusage.getUsed(), false),
141 humanReadableByteCount(memusage.getCommitted(), false),
142 freeratio * 100
143 );
144 }
145 }