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
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/sun.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 REGION_SIZE = 1 * 1024 * 1024;
55
56 public static void main(String[] args) throws Exception, Throwable {
57 ProcessBuilder pb = ProcessTools.createJavaProcessBuilder(
58 "-XX:InitialHeapSize=" + INITIAL_HEAP_SIZE,
59 "-Xmn" + MINIMAL_YOUNG_SIZE,
60 "-XX:MinHeapFreeRatio=10",
61 "-XX:MaxHeapFreeRatio=11",
62 "-XX:+UseG1GC",
63 "-XX:G1HeapRegionSize=" + REGION_SIZE,
64 "-XX:-ExplicitGCInvokesConcurrent",
65 "-verbose:gc",
66 GCTest.class.getName()
67 );
68
69 OutputAnalyzer output = ProcessTools.executeProcess(pb);
70 output.shouldHaveExitValue(0);
71 }
72
73 static class GCTest {
74
75 private static final String MIN_FREE_RATIO_FLAG_NAME = "MinHeapFreeRatio";
76 private static final String MAX_FREE_RATIO_FLAG_NAME = "MaxHeapFreeRatio";
77 private static final String NEW_SIZE_FLAG_NAME = "NewSize";
78
79 private static final ArrayList<ArrayList<byte[]>> garbage = new ArrayList<>();
80
81 private static final int SMALL_OBJS_SIZE = 10 * 1024; // 10kB
82 private static final int SMALL_OBJS_COUNT = MINIMAL_YOUNG_SIZE / (SMALL_OBJS_SIZE-1);
83 private static final int ALLOCATE_COUNT = 3;
84 // try to put all humongous object into gap between min young size and initial heap size
85 // to avoid implicit GCs
86 private static final int HUMONG_OBJS_SIZE = (int) Math.max(
87 (INITIAL_HEAP_SIZE - MINIMAL_YOUNG_SIZE) / ALLOCATE_COUNT / 4,
88 REGION_SIZE * 1.1
89 );
90
91 private static final long initialHeapSize = getHeapMemoryUsage().getUsed();
92
93 public static void main(String[] args) throws InterruptedException {
94 new GCTest().test();
95 }
96
97 private void test() throws InterruptedException {
98 MemoryUsagePrinter.printMemoryUsage("init");
99
100 allocate();
101 System.gc();
102 MemoryUsage muFull = getHeapMemoryUsage();
103 MemoryUsagePrinter.printMemoryUsage("allocated");
104
105 free();
106 //Thread.sleep(1000); // sleep before measures due lags in JMX
107 MemoryUsage muFree = getHeapMemoryUsage();
108 MemoryUsagePrinter.printMemoryUsage("free");
109
110 assertLessThan(muFree.getCommitted(), muFull.getCommitted(), prepareMessageCommittedIsNotLess() );
111 }
112
113 private void allocate() {
114 System.out.format("Will allocate objects of small size = %s and humongous size = %s",
115 MemoryUsagePrinter.humanReadableByteCount(SMALL_OBJS_SIZE, false),
116 MemoryUsagePrinter.humanReadableByteCount(HUMONG_OBJS_SIZE, false)
117 );
118
119 for (int i = 0; i < ALLOCATE_COUNT; i++) {
120 ArrayList<byte[]> stuff = new ArrayList<>();
121 allocateList(stuff, SMALL_OBJS_COUNT / ALLOCATE_COUNT, SMALL_OBJS_SIZE);
122 garbage.add(stuff);
123
124 ArrayList<byte[]> humongousStuff = new ArrayList<>();
125 allocateList(humongousStuff, 4, HUMONG_OBJS_SIZE);
126 garbage.add(humongousStuff);
127 }
128 }
129
130 private void free() {
131 // do not free last one list
132 garbage.subList(0, garbage.size() - 1).clear();
133
134 // do not free last one element from last list
135 ArrayList stuff = garbage.get(garbage.size() - 1);
136 if (stuff.size() > 1) {
137 stuff.subList(0, stuff.size() - 1).clear();
138 }
139 System.gc();
140 }
141
142 private String prepareMessageCommittedIsNotLess() {
143 return String.format(
144 "committed free heap size is not less than committed full heap size, heap hasn't been shrunk?%n"
145 + "%s = %s%n%s = %s",
146 MIN_FREE_RATIO_FLAG_NAME,
147 ManagementFactory.getPlatformMXBean(HotSpotDiagnosticMXBean.class)
148 .getVMOption(MIN_FREE_RATIO_FLAG_NAME).getValue(),
149 MAX_FREE_RATIO_FLAG_NAME,
150 ManagementFactory.getPlatformMXBean(HotSpotDiagnosticMXBean.class)
151 .getVMOption(MAX_FREE_RATIO_FLAG_NAME).getValue()
152 );
153 }
154
155 private static void allocateList(List garbage, int count, int size) {
156 for (int i = 0; i < count; i++) {
157 garbage.add(new byte[size]);
158 }
159 }
160 }
161
162 static MemoryUsage getHeapMemoryUsage() {
163 return ManagementFactory.getMemoryMXBean().getHeapMemoryUsage();
164 }
165
166 /**
167 * Prints memory usage to standard output
168 */
169 static class MemoryUsagePrinter {
170
171 public static String humanReadableByteCount(long bytes, boolean si) {
172 int unit = si ? 1000 : 1024;
173 if (bytes < unit) {
174 return bytes + " B";
175 }
176 int exp = (int) (Math.log(bytes) / Math.log(unit));
177 String pre = (si ? "kMGTPE" : "KMGTPE").charAt(exp - 1) + (si ? "" : "i");
178 return String.format("%.1f %sB", bytes / Math.pow(unit, exp), pre);
179 }
180
181 public static void printMemoryUsage(String label) {
182 MemoryUsage memusage = ManagementFactory.getMemoryMXBean().getHeapMemoryUsage();
183 float freeratio = 1f - (float) memusage.getUsed() / memusage.getCommitted();
184 System.out.format("[%-24s] init: %-7s, used: %-7s, comm: %-7s, freeRatio ~= %.1f%%%n",
185 label,
186 humanReadableByteCount(memusage.getInit(), false),
187 humanReadableByteCount(memusage.getUsed(), false),
188 humanReadableByteCount(memusage.getCommitted(), false),
189 freeratio * 100
190 );
191 }
192 }
193 }