1 /*
2 * Copyright (c) 2014, 2015, 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 TestShrinkDefragmentedHeap
26 * @bug 8038423 8129590
27 * @summary Verify that heap shrinks after GC in the presence of fragmentation due to humongous objects
28 * 1. allocate small objects mixed with humongous ones
29 * "ssssHssssHssssHssssHssssHssssHssssH"
30 * 2. release all allocated object except the last humongous one
31 * "..................................H"
32 * 3. invoke gc and check that memory returned to the system (amount of committed memory got down)
33 *
34 * @library /testlibrary
35 * @modules java.base/jdk.internal.misc
36 * java.management/sun.management
37 */
38 import java.lang.management.ManagementFactory;
39 import java.lang.management.MemoryUsage;
40 import java.util.ArrayList;
41 import java.util.List;
42 import static jdk.test.lib.Asserts.*;
43 import jdk.test.lib.ProcessTools;
44 import jdk.test.lib.OutputAnalyzer;
45 import com.sun.management.HotSpotDiagnosticMXBean;
46
47 public class TestShrinkDefragmentedHeap {
48 // Since we store all the small objects, they become old and old regions are also allocated at the bottom of the heap
49 // together with humongous regions. So if there are a lot of old regions in the lower part of the heap,
50 // the humongous regions will be allocated in the upper part of the heap anyway.
51 // To avoid this the Eden needs to be big enough to fit all the small objects.
52 private static final int INITIAL_HEAP_SIZE = 200 * 1024 * 1024;
53 private static final int MINIMAL_YOUNG_SIZE = 190 * 1024 * 1024;
54 private static final int MAXIMUM_HEAP_SIZE = 256 * 1024 * 1024;
55 private static final int REGION_SIZE = 1 * 1024 * 1024;
56
57 public static void main(String[] args) throws Exception, Throwable {
58 ProcessBuilder pb = ProcessTools.createJavaProcessBuilder(
59 "-XX:InitialHeapSize=" + INITIAL_HEAP_SIZE,
60 "-Xmn" + MINIMAL_YOUNG_SIZE,
61 "-Xmx" + MAXIMUM_HEAP_SIZE,
62 "-XX:MinHeapFreeRatio=10",
63 "-XX:MaxHeapFreeRatio=11",
64 "-XX:+UseG1GC",
65 "-XX:G1HeapRegionSize=" + REGION_SIZE,
66 "-XX:-ExplicitGCInvokesConcurrent",
67 "-verbose:gc",
68 GCTest.class.getName()
69 );
70
71 OutputAnalyzer output = ProcessTools.executeProcess(pb);
72 output.shouldHaveExitValue(0);
73 }
74
75 static class GCTest {
76
77 private static final String MIN_FREE_RATIO_FLAG_NAME = "MinHeapFreeRatio";
78 private static final String MAX_FREE_RATIO_FLAG_NAME = "MaxHeapFreeRatio";
79 private static final String NEW_SIZE_FLAG_NAME = "NewSize";
80
81 private static final ArrayList<ArrayList<byte[]>> garbage = new ArrayList<>();
82
83 private static final int SMALL_OBJS_SIZE = 10 * 1024; // 10kB
84 private static final int SMALL_OBJS_COUNT = MINIMAL_YOUNG_SIZE / (SMALL_OBJS_SIZE-1);
85 private static final int ALLOCATE_COUNT = 3;
86 // try to put all humongous object into gap between min young size and initial heap size
87 // to avoid implicit GCs
88 private static final int HUMONG_OBJS_SIZE = (int) Math.max(
89 (INITIAL_HEAP_SIZE - MINIMAL_YOUNG_SIZE) / ALLOCATE_COUNT / 4,
90 REGION_SIZE * 1.1
91 );
92
93 private static final long initialHeapSize = getHeapMemoryUsage().getUsed();
94
95 public static void main(String[] args) throws InterruptedException {
96 new GCTest().test();
97 }
98
99 private void test() throws InterruptedException {
100 MemoryUsagePrinter.printMemoryUsage("init");
101
102 allocate();
103 System.gc();
104 MemoryUsage muFull = getHeapMemoryUsage();
105 MemoryUsagePrinter.printMemoryUsage("allocated");
106
107 free();
108 //Thread.sleep(1000); // sleep before measures due lags in JMX
109 MemoryUsage muFree = getHeapMemoryUsage();
110 MemoryUsagePrinter.printMemoryUsage("free");
111
112 assertLessThan(muFree.getCommitted(), muFull.getCommitted(), prepareMessageCommittedIsNotLess() );
113 }
114
115 private void allocate() {
116 System.out.format("Will allocate objects of small size = %s and humongous size = %s",
117 MemoryUsagePrinter.humanReadableByteCount(SMALL_OBJS_SIZE, false),
118 MemoryUsagePrinter.humanReadableByteCount(HUMONG_OBJS_SIZE, false)
119 );
120
121 for (int i = 0; i < ALLOCATE_COUNT; i++) {
122 ArrayList<byte[]> stuff = new ArrayList<>();
123 allocateList(stuff, SMALL_OBJS_COUNT / ALLOCATE_COUNT, SMALL_OBJS_SIZE);
124 garbage.add(stuff);
125
126 ArrayList<byte[]> humongousStuff = new ArrayList<>();
127 allocateList(humongousStuff, 4, HUMONG_OBJS_SIZE);
128 garbage.add(humongousStuff);
129 }
130 }
131
132 private void free() {
133 // do not free last one list
134 garbage.subList(0, garbage.size() - 1).clear();
135
136 // do not free last one element from last list
137 ArrayList stuff = garbage.get(garbage.size() - 1);
138 if (stuff.size() > 1) {
139 stuff.subList(0, stuff.size() - 1).clear();
140 }
141 System.gc();
142 }
143
144 private String prepareMessageCommittedIsNotLess() {
145 return String.format(
146 "committed free heap size is not less than committed full heap size, heap hasn't been shrunk?%n"
147 + "%s = %s%n%s = %s",
148 MIN_FREE_RATIO_FLAG_NAME,
149 ManagementFactory.getPlatformMXBean(HotSpotDiagnosticMXBean.class)
150 .getVMOption(MIN_FREE_RATIO_FLAG_NAME).getValue(),
151 MAX_FREE_RATIO_FLAG_NAME,
152 ManagementFactory.getPlatformMXBean(HotSpotDiagnosticMXBean.class)
153 .getVMOption(MAX_FREE_RATIO_FLAG_NAME).getValue()
154 );
155 }
156
157 private static void allocateList(List garbage, int count, int size) {
158 for (int i = 0; i < count; i++) {
159 garbage.add(new byte[size]);
160 }
161 }
162 }
163
164 static MemoryUsage getHeapMemoryUsage() {
165 return ManagementFactory.getMemoryMXBean().getHeapMemoryUsage();
166 }
167
168 /**
169 * Prints memory usage to standard output
170 */
171 static class MemoryUsagePrinter {
172
173 public static String humanReadableByteCount(long bytes, boolean si) {
174 int unit = si ? 1000 : 1024;
175 if (bytes < unit) {
176 return bytes + " B";
177 }
178 int exp = (int) (Math.log(bytes) / Math.log(unit));
179 String pre = (si ? "kMGTPE" : "KMGTPE").charAt(exp - 1) + (si ? "" : "i");
180 return String.format("%.1f %sB", bytes / Math.pow(unit, exp), pre);
181 }
182
183 public static void printMemoryUsage(String label) {
184 MemoryUsage memusage = ManagementFactory.getMemoryMXBean().getHeapMemoryUsage();
185 float freeratio = 1f - (float) memusage.getUsed() / memusage.getCommitted();
186 System.out.format("[%-24s] init: %-7s, used: %-7s, comm: %-7s, freeRatio ~= %.1f%%%n",
187 label,
188 humanReadableByteCount(memusage.getInit(), false),
189 humanReadableByteCount(memusage.getUsed(), false),
190 humanReadableByteCount(memusage.getCommitted(), false),
191 freeratio * 100
192 );
193 }
194 }
195 }