1 /*
2 * Copyright (c) 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
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22 */
23
24 /*
25 * @test TestGreyReclaimedHumongousObjects.java
26 * @bug 8069367
27 * @requires vm.gc == "G1" | vm.gc == "null"
28 * @summary Test handling of marked but unscanned reclaimed humongous objects.
29 * @key gc
30 * @run main/othervm -XX:+UseG1GC -Xss32m -Xmx128m -XX:G1HeapRegionSize=1m
31 * -XX:+UnlockExperimentalVMOptions
32 * -XX:+G1EagerReclaimHumongousObjects
33 * -XX:+G1EagerReclaimHumongousObjectsWithStaleRefs
34 * TestGreyReclaimedHumongousObjects 1048576 90
35 */
36
37 // This test spawns a bunch of threads, each of them rapidly
38 // allocating large objects and storing them into a circular buffer
39 // associated with the thread. The circular buffer results in these
40 // objects becoming dead in fairly short order.
41 //
42 // The situation we're trying to provoke is
43 //
44 // (1) A humongous object H is marked and added to the mark stack.
45 //
46 // (2) An evacuation pause determines H is no longer live, and
47 // reclaims it. This occurs before concurrent marking has gotten
48 // around to processing the mark stack entry for H.
49 //
50 // (3) Concurrent marking processes the mark stack entry for H. The
51 // bug is that it would attempt to scan the now dead object.
52 //
53 // Unfortunately, this test is *very* sensitive to configuration.
54 // Among the parameters that affect whether / how often we'll get into
55 // the desired situation within a reasonable amount of time are:
56 //
57 // - THREAD_COUNT: The number of allocating threads.
58 //
59 // - OLD_COUNT: The number of objects each thread keeps.
60 //
61 // - MAX_MEMORY: The maximum heap size.
62 //
63 // - G1HeapRegionSize
64 //
65 // - The size of the objects being allocated.
66 //
67 // The parameter values specified here:
68 //
69 // - THREAD_COUNT = 12
70 // - OLD_COUNT == 4
71 // - MAX_MEMORY == 128m
72 // - G1HeapRegionSize = 1m
73 // - Object size = 1048576 (2 regions after header overhead and roundup)
74 //
75 // seems to work well at provoking the desired state fairly quickly.
76 // Even relatively small perturbations may change that. The key
77 // factors seem to be keeping the heap mostly full of live objects but
78 // having them become dead fairly quickly.
79
80 import java.util.Date;
81 import java.util.concurrent.ExecutorService;
82 import java.util.concurrent.Executors;
83 import java.util.concurrent.ThreadFactory;
84 import java.util.concurrent.TimeUnit;
85 import sun.management.ManagementFactoryHelper;
86 import com.sun.management.HotSpotDiagnosticMXBean;
87 import com.sun.management.VMOption;
88
89 public class TestGreyReclaimedHumongousObjects {
90
91 static class NamedThreadFactory implements ThreadFactory {
92 private int threadNum = 0;
93
94 @Override
95 public Thread newThread(Runnable r) {
96 return new Thread(r, THREAD_NAME + (threadNum++));
97 }
98 }
99
100 static class Runner extends Thread {
101 private final Date startDate = new Date();
102 private final int obj_size;
103 private final Object[] old_garbage;
104 private int old_index = 0;
105
106 public Runner(int obj_size) {
107 this.obj_size = obj_size;
108 old_garbage = new Object[OLD_COUNT];
109 }
110
111 private void allocate_garbage() {
112 byte[] garbage = new byte[obj_size];
113 old_garbage[Math.abs(++old_index % OLD_COUNT)] = garbage;
114 }
115
116 @Override
117 public void run() {
118 try {
119 while (!isInterrupted()) {
120 allocate_garbage();
121 Thread.sleep(0); // Yield, to ensure interruptable.
122 }
123 } catch (InterruptedException e) {
124 System.out.println("Aborted after "
125 + (new Date().getTime() - startDate.getTime())
126 + " ms");
127 interrupt();
128 }
129 }
130 }
131
132 public static void main(String[] args) throws Exception {
133 HotSpotDiagnosticMXBean diagnostic = ManagementFactoryHelper.getDiagnosticMXBean();
134
135 System.out.println("Max memory= " + MAX_MEMORY + " bytes");
136
137 int obj_size = 0;
138 long seconds_to_run = 0;
139 if (args.length != 2) {
140 throw new RuntimeException("Object size argument must be supplied");
141 } else {
142 obj_size = Integer.parseInt(args[0]);
143 seconds_to_run = Integer.parseInt(args[1]);
144 }
145 System.out.println("Objects size= " + obj_size + " bytes");
146 System.out.println("Seconds to run=" + seconds_to_run);
147
148 int region_size =
149 Integer.parseInt(diagnostic.getVMOption("G1HeapRegionSize").getValue());
150 if (obj_size < (region_size / 2)) {
151 throw new RuntimeException("Object size " + obj_size +
152 " is not humongous with region size " + region_size);
153 }
154
155 ExecutorService executor =
156 Executors.newFixedThreadPool(THREAD_COUNT, new NamedThreadFactory());
157 System.out.println("Starting " + THREAD_COUNT + " threads");
158
159 for (int i = 0; i < THREAD_COUNT; i++) {
160 executor.execute(new Runner(obj_size));
161 }
162
163 Thread.sleep(seconds_to_run * 1000);
164 executor.shutdownNow();
165
166 if (!executor.awaitTermination(10, TimeUnit.SECONDS)) {
167 System.err.println("Thread pool did not terminate after 10 seconds after shutdown");
168 }
169 }
170
171 private static final long MAX_MEMORY = Runtime.getRuntime().maxMemory();
172 private static final int OLD_COUNT = 4;
173 private static final int THREAD_COUNT = 12;
174 private static final String THREAD_NAME = "TestGreyRH-";
175 }
176