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