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