1 /*
2 * Copyright (c) 2014, 2016, 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
28 * @summary Verify that heap shrinks after GC in the presence of fragmentation
29 * due to humongous objects
30 * @library /test/lib
31 * @modules java.base/jdk.internal.misc
32 * @modules java.management/sun.management
33 * @run main/othervm -XX:-ExplicitGCInvokesConcurrent -XX:MinHeapFreeRatio=10
34 * -XX:MaxHeapFreeRatio=12 -XX:+UseG1GC -XX:G1HeapRegionSize=1M -verbose:gc
35 * TestHumongousShrinkHeap
36 */
37
38 import com.sun.management.HotSpotDiagnosticMXBean;
39 import java.lang.management.ManagementFactory;
40 import java.lang.management.MemoryUsage;
41 import java.util.ArrayList;
42 import java.util.List;
43 import static jdk.test.lib.Asserts.*;
44
45 public class TestHumongousShrinkHeap {
46
47 public static final String MIN_FREE_RATIO_FLAG_NAME = "MinHeapFreeRatio";
48 public static final String MAX_FREE_RATIO_FLAG_NAME = "MaxHeapFreeRatio";
49
50 private static final List<List<byte[]>> garbage = new ArrayList();
51 private static final int REGION_SIZE = 1024 * 1024; // 1M
52 private static final int LISTS_COUNT = 10;
53 private static final int HUMON_SIZE = Math.round(.9f * REGION_SIZE);
54 private static final long AVAILABLE_MEMORY
55 = Runtime.getRuntime().freeMemory();
56 private static final int HUMON_COUNT
57 = (int) ((AVAILABLE_MEMORY / HUMON_SIZE)
58 / LISTS_COUNT);
59
60
61 public static void main(String[] args) {
62 if (HUMON_COUNT == 0) {
63 System.out.println("Skipped. Heap is too small");
64 return;
65 }
66 System.out.format("Running with %s max heap size. "
67 + "Will allocate humongous object of %s size %d times.%n",
68 MemoryUsagePrinter.humanReadableByteCount(AVAILABLE_MEMORY, false),
69 MemoryUsagePrinter.humanReadableByteCount(HUMON_SIZE, false),
70 HUMON_COUNT
71 );
72 new TestHumongousShrinkHeap().test();
73 }
74
75 private final void test() {
76 System.gc();
77 MemoryUsagePrinter.printMemoryUsage("init");
78
79 allocate();
80 MemoryUsagePrinter.printMemoryUsage("allocated");
81 MemoryUsage muFull = ManagementFactory.getMemoryMXBean().getHeapMemoryUsage();
82
83 free();
84 MemoryUsagePrinter.printMemoryUsage("free");
85 MemoryUsage muFree = ManagementFactory.getMemoryMXBean().getHeapMemoryUsage();
86
87 assertLessThan(muFree.getCommitted(), muFull.getCommitted(), String.format(
88 "committed free heap size is not less than committed full heap size, heap hasn't been shrunk?%n"
89 + "%s = %s%n%s = %s",
90 MIN_FREE_RATIO_FLAG_NAME,
91 ManagementFactory.getPlatformMXBean(HotSpotDiagnosticMXBean.class)
92 .getVMOption(MIN_FREE_RATIO_FLAG_NAME).getValue(),
93 MAX_FREE_RATIO_FLAG_NAME,
94 ManagementFactory.getPlatformMXBean(HotSpotDiagnosticMXBean.class)
95 .getVMOption(MAX_FREE_RATIO_FLAG_NAME).getValue()
96 ));
97 }
98
99 private void allocate() {
100
101 for (int i = 0; i < LISTS_COUNT; i++) {
102 List<byte[]> stuff = new ArrayList();
103 allocateList(stuff, HUMON_COUNT, HUMON_SIZE);
104 MemoryUsagePrinter.printMemoryUsage("allocate #" + (i+1));
105 garbage.add(stuff);
106 }
107 }
108
109 private void free() {
110 // do not free last one list
111 garbage.subList(0, garbage.size() - 1).clear();
112
113 // do not free last one element from last list
114 List stuff = garbage.get(garbage.size() - 1);
115 stuff.subList(0, stuff.size() - 1).clear();
116 System.gc();
117 }
118
119 private static void allocateList(List garbage, int count, int size) {
120 for (int i = 0; i < count; i++) {
121 garbage.add(new byte[size]);
122 }
123 }
124 }
125
126 /**
127 * Prints memory usage to standard output
128 */
129 class MemoryUsagePrinter {
130
131 public static String humanReadableByteCount(long bytes, boolean si) {
132 int unit = si ? 1000 : 1024;
133 if (bytes < unit) {
134 return bytes + " B";
135 }
136 int exp = (int) (Math.log(bytes) / Math.log(unit));
137 String pre = (si ? "kMGTPE" : "KMGTPE").charAt(exp - 1) + (si ? "" : "i");
138 return String.format("%.1f %sB", bytes / Math.pow(unit, exp), pre);
139 }
140
141 public static void printMemoryUsage(String label) {
142 MemoryUsage memusage = ManagementFactory.getMemoryMXBean().getHeapMemoryUsage();
143 float freeratio = 1f - (float) memusage.getUsed() / memusage.getCommitted();
144 System.out.format("[%-24s] init: %-7s, used: %-7s, comm: %-7s, freeRatio ~= %.1f%%%n",
145 label,
146 humanReadableByteCount(memusage.getInit(), false),
147 humanReadableByteCount(memusage.getUsed(), false),
148 humanReadableByteCount(memusage.getCommitted(), false),
149 freeratio * 100
150 );
151 }
152 }