1 /*
2 * Copyright (c) 2014, 2019, 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 package gc.g1;
25
26 /**
27 * @test TestShrinkDefragmentedHeap
28 * @bug 8038423 8129590
29 * @summary Verify that heap shrinks after GC in the presence of fragmentation due to humongous objects
30 * 1. allocate small objects mixed with humongous ones
31 * "ssssHssssHssssHssssHssssHssssHssssH"
32 * 2. release all allocated object except the last humongous one
33 * "..................................H"
34 * 3. invoke gc and check that memory returned to the system (amount of committed memory got down)
35 *
36 * @library /test/lib /
37 * @requires vm.gc.G1
38 * @modules java.base/jdk.internal.misc
39 * java.management/sun.management
40 * @run main gc.g1.TestShrinkDefragmentedHeap
41 */
42 import java.lang.management.ManagementFactory;
43 import java.lang.management.MemoryUsage;
44 import java.util.ArrayList;
45 import java.util.List;
46 import java.text.NumberFormat;
47 import static jdk.test.lib.Asserts.*;
48 import jdk.test.lib.process.OutputAnalyzer;
49 import jdk.test.lib.process.ProcessTools;
50 import com.sun.management.HotSpotDiagnosticMXBean;
51 import gc.testlibrary.Helpers;
52
53 public class TestShrinkDefragmentedHeap {
54 // Since we store all the small objects, they become old and old regions are also allocated at the bottom of the heap
55 // together with humongous regions. So if there are a lot of old regions in the lower part of the heap,
56 // the humongous regions will be allocated in the upper part of the heap anyway.
57 // To avoid this the Eden needs to be big enough to fit all the small objects.
58 private static final int INITIAL_HEAP_SIZE = 200 * 1024 * 1024;
59 private static final int MINIMAL_YOUNG_SIZE = 190 * 1024 * 1024;
60 private static final int MAXIMUM_HEAP_SIZE = 256 * 1024 * 1024;
61 private static final int REGION_SIZE = 1 * 1024 * 1024;
62
63 public static void main(String[] args) throws Exception, Throwable {
64 ProcessBuilder pb = ProcessTools.createJavaProcessBuilder(
65 "-XX:InitialHeapSize=" + INITIAL_HEAP_SIZE,
66 "-Xmn" + MINIMAL_YOUNG_SIZE,
67 "-Xmx" + MAXIMUM_HEAP_SIZE,
68 "-XX:MinHeapFreeRatio=10",
69 "-XX:MaxHeapFreeRatio=11",
70 "-XX:+UseG1GC",
71 "-XX:G1HeapRegionSize=" + REGION_SIZE,
72 "-XX:-ExplicitGCInvokesConcurrent",
73 "-verbose:gc",
74 GCTest.class.getName()
75 );
76
77 OutputAnalyzer output = ProcessTools.executeProcess(pb);
78 output.shouldHaveExitValue(0);
79 }
80
81 static class GCTest {
82
83 private static final String MIN_FREE_RATIO_FLAG_NAME = "MinHeapFreeRatio";
84 private static final String MAX_FREE_RATIO_FLAG_NAME = "MaxHeapFreeRatio";
85 private static final String NEW_SIZE_FLAG_NAME = "NewSize";
86
87 private static final ArrayList<ArrayList<byte[]>> garbage = new ArrayList<>();
88
89 private static final int SMALL_OBJS_SIZE = 10 * 1024; // 10kB
90 private static final int SMALL_OBJS_COUNT = MINIMAL_YOUNG_SIZE / (SMALL_OBJS_SIZE-1);
91 private static final int ALLOCATE_COUNT = 3;
92 // try to put all humongous object into gap between min young size and initial heap size
93 // to avoid implicit GCs
94 private static final int HUMONG_OBJS_SIZE = (int) Math.max(
95 (INITIAL_HEAP_SIZE - MINIMAL_YOUNG_SIZE) / ALLOCATE_COUNT / 4,
96 REGION_SIZE * 1.1
97 );
98
99 private static final long initialHeapSize = getHeapMemoryUsage().getUsed();
100
101 public static void main(String[] args) throws InterruptedException {
102 new GCTest().test();
103 }
104
105 private void test() throws InterruptedException {
106 MemoryUsagePrinter.printMemoryUsage("init");
107
108 allocate();
109 System.gc();
110 MemoryUsage muFull = getHeapMemoryUsage();
111 MemoryUsagePrinter.printMemoryUsage("allocated");
112
113 free();
114 //Thread.sleep(1000); // sleep before measures due lags in JMX
115 MemoryUsage muFree = getHeapMemoryUsage();
116 MemoryUsagePrinter.printMemoryUsage("free");
117
118 assertLessThan(muFree.getCommitted(), muFull.getCommitted(), prepareMessageCommittedIsNotLess() );
119 }
120
121 private void allocate() {
122 System.out.format("Will allocate objects of small size = %s and humongous size = %s",
123 MemoryUsagePrinter.NF.format(SMALL_OBJS_SIZE),
124 MemoryUsagePrinter.NF.format(HUMONG_OBJS_SIZE)
125 );
126
127 for (int i = 0; i < ALLOCATE_COUNT; i++) {
128 ArrayList<byte[]> stuff = new ArrayList<>();
129 allocateList(stuff, SMALL_OBJS_COUNT / ALLOCATE_COUNT, SMALL_OBJS_SIZE);
130 garbage.add(stuff);
131
132 ArrayList<byte[]> humongousStuff = new ArrayList<>();
133 allocateList(humongousStuff, 4, HUMONG_OBJS_SIZE);
134 garbage.add(humongousStuff);
135 }
136 }
137
138 private void free() {
139 // do not free last one list
140 garbage.subList(0, garbage.size() - 1).clear();
141
142 // do not free last one element from last list
143 ArrayList<byte[]> stuff = garbage.get(garbage.size() - 1);
144 if (stuff.size() > 1) {
145 stuff.subList(0, stuff.size() - 1).clear();
146 }
147 System.gc();
148 }
149
150 private String prepareMessageCommittedIsNotLess() {
151 return String.format(
152 "committed free heap size is not less than committed full heap size, heap hasn't been shrunk?%n"
153 + "%s = %s%n%s = %s",
154 MIN_FREE_RATIO_FLAG_NAME,
155 ManagementFactory.getPlatformMXBean(HotSpotDiagnosticMXBean.class)
156 .getVMOption(MIN_FREE_RATIO_FLAG_NAME).getValue(),
157 MAX_FREE_RATIO_FLAG_NAME,
158 ManagementFactory.getPlatformMXBean(HotSpotDiagnosticMXBean.class)
159 .getVMOption(MAX_FREE_RATIO_FLAG_NAME).getValue()
160 );
161 }
162
163 private static void allocateList(List<byte[]> garbage, int count, int size) {
164 for (int i = 0; i < count; i++) {
165 garbage.add(new byte[size]);
166 }
167 }
168 }
169
170 static MemoryUsage getHeapMemoryUsage() {
171 return ManagementFactory.getMemoryMXBean().getHeapMemoryUsage();
172 }
173
174 /**
175 * Prints memory usage to standard output
176 */
177 static class MemoryUsagePrinter {
178
179 public static final NumberFormat NF = Helpers.numberFormatter();
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 NF.format(memusage.getInit()),
187 NF.format(memusage.getUsed()),
188 NF.format(memusage.getCommitted()),
189 freeratio * 100
190 );
191 }
192 }
193 }