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