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