1 /*
2 * Copyright (c) 2014, 2016, 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 TestSmallHeap
26 * @bug 8067438 8152239
27 * @requires vm.gc=="null"
28 * @summary Verify that starting the VM with a small heap works
29 * @library /testlibrary /test/lib /test/lib/share/classes
30 * @ignore 8161552
31 * @modules java.base/jdk.internal.misc
32 * @modules java.management/sun.management
33 * @build TestSmallHeap
34 * @run main ClassFileInstaller sun.hotspot.WhiteBox
35 * @run main/othervm -Xbootclasspath/a:. -XX:+UnlockDiagnosticVMOptions -XX:+WhiteBoxAPI TestSmallHeap
36 */
37
38 /* Note: It would be nice to verify the minimal supported heap size (2m) here,
39 * but we align the heap size based on the card table size. And the card table
40 * size is aligned based on the minimal pages size provided by the os. This
41 * means that on most platforms, where the minimal page size is 4k, we get a
42 * minimal heap size of 2m but on Solaris/Sparc we have a page size of 8k and
43 * get a minimal heap size of 4m. And on platforms where the page size is 64k
44 * we get a minimal heap size of 32m. We never use large pages for the card table.
45 *
46 * There is also no check in the VM for verifying that the maximum heap size
47 * is larger than the supported minimal heap size. This means that specifying
48 * -Xmx1m on the command line is fine but will give a heap of 2m (or 4m or 32m).
49 *
50 * To work around these rather strange behaviors this test uses -Xmx2m but then
51 * calculates what the expected heap size should be. The calculation is a
52 * simplified version of the code in the VM. We assume that the card table will
53 * use one page. Each byte in the card table corresponds to 512 bytes on the heap.
54 * So, the expected heap size is page_size * 512.
55 */
56
57 import jdk.test.lib.Asserts;
58 import jdk.test.lib.process.OutputAnalyzer;
59 import jdk.test.lib.process.ProcessTools;
60
61 import java.util.LinkedList;
62
63 import sun.hotspot.WhiteBox;
64
65 public class TestSmallHeap {
66
67 public static void main(String[] args) throws Exception {
68 // Do all work in the VM driving the test, the VM
69 // with the small heap size should do as little as
70 // possible to avoid hitting an OOME.
71 WhiteBox wb = WhiteBox.getWhiteBox();
72 int pageSize = wb.getVMPageSize();
73 int heapBytesPerCard = 512;
74 long expectedMaxHeap = pageSize * heapBytesPerCard;
75
76 verifySmallHeapSize("-XX:+UseParallelGC", expectedMaxHeap);
77 verifySmallHeapSize("-XX:+UseSerialGC", expectedMaxHeap);
78 verifySmallHeapSize("-XX:+UseG1GC", expectedMaxHeap);
79 verifySmallHeapSize("-XX:+UseConcMarkSweepGC", expectedMaxHeap);
80 }
81
82 private static void verifySmallHeapSize(String gc, long expectedMaxHeap) throws Exception {
83 LinkedList<String> vmOptions = new LinkedList<>();
84 vmOptions.add(gc);
85 vmOptions.add("-Xmx2m");
86 vmOptions.add("-XX:+PrintFlagsFinal");
87 vmOptions.add(VerifyHeapSize.class.getName());
88
89 ProcessBuilder pb = ProcessTools.createJavaProcessBuilder(vmOptions.toArray(new String[0]));
90 OutputAnalyzer analyzer = new OutputAnalyzer(pb.start());
91 analyzer.shouldHaveExitValue(0);
92
93 long maxHeapSize = Long.parseLong(analyzer.firstMatch("MaxHeapSize.+=\\s+(\\d+)",1));
94 long actualHeapSize = Long.parseLong(analyzer.firstMatch(VerifyHeapSize.actualMsg + "(\\d+)",1));
95 Asserts.assertEQ(maxHeapSize, expectedMaxHeap);
96 Asserts.assertLessThanOrEqual(actualHeapSize, maxHeapSize);
97 }
98 }
99
100 class VerifyHeapSize {
101 public static final String actualMsg = "Actual heap size: ";
102
103 public static void main(String args[]) {
104 // Avoid string concatenation
105 System.out.print(actualMsg);
106 System.out.println(Runtime.getRuntime().maxMemory());
107 }
108 }