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 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.
47 *
48 * To work around these behaviors this test uses -Xmx4m but then
49 * calculates what the expected heap size should be. The calculation is a
50 * simplified version of the code in the VM. We assume that the card table will
51 * use one page. Each byte in the card table corresponds to 512 bytes on the heap.
52 * So, the expected heap size is page_size * 512.
53 *
54 * There is no formal requirement for the minimal value of the maximum heap size
55 * the VM should support. In most cases the VM could start with -Xmx2m.
56 * But with 2m limit GC could be triggered before VM initialization completed.
57 * Therefore we start the VM with 4M heap.
58 */
59
60 import jdk.test.lib.Asserts;
61 import jdk.test.lib.process.OutputAnalyzer;
62 import jdk.test.lib.process.ProcessTools;
63
64 import java.util.LinkedList;
65
66 import sun.hotspot.WhiteBox;
67
68 public class TestSmallHeap {
69
70 public static void main(String[] args) throws Exception {
71 // Do all work in the VM driving the test, the VM
72 // with the small heap size should do as little as
73 // possible to avoid hitting an OOME.
74 WhiteBox wb = WhiteBox.getWhiteBox();
75 int pageSize = wb.getVMPageSize();
76 int heapBytesPerCard = 512;
77 long expectedMaxHeap = pageSize * heapBytesPerCard;
78
79 verifySmallHeapSize("-XX:+UseParallelGC", expectedMaxHeap);
80 verifySmallHeapSize("-XX:+UseSerialGC", expectedMaxHeap);
81 verifySmallHeapSize("-XX:+UseG1GC", expectedMaxHeap);
82 verifySmallHeapSize("-XX:+UseConcMarkSweepGC", expectedMaxHeap);
83 }
84
85 private static void verifySmallHeapSize(String gc, long expectedMaxHeap) throws Exception {
86 long minMaxHeap = 4 * 1024 * 1024;
87 LinkedList<String> vmOptions = new LinkedList<>();
88 vmOptions.add(gc);
89 vmOptions.add("-Xmx" + minMaxHeap);
90 vmOptions.add("-XX:+PrintFlagsFinal");
91 vmOptions.add(VerifyHeapSize.class.getName());
92
93 ProcessBuilder pb = ProcessTools.createJavaProcessBuilder(vmOptions.toArray(new String[0]));
94 OutputAnalyzer analyzer = new OutputAnalyzer(pb.start());
95 analyzer.shouldHaveExitValue(0);
96
97 expectedMaxHeap = Math.max(expectedMaxHeap, minMaxHeap);
98 long maxHeapSize = Long.parseLong(analyzer.firstMatch("MaxHeapSize.+=\\s+(\\d+)",1));
99 long actualHeapSize = Long.parseLong(analyzer.firstMatch(VerifyHeapSize.actualMsg + "(\\d+)",1));
100 Asserts.assertEQ(maxHeapSize, expectedMaxHeap);
101 Asserts.assertLessThanOrEqual(actualHeapSize, maxHeapSize);
102 }
103 }
104
105 class VerifyHeapSize {
106 public static final String actualMsg = "Actual heap size: ";
107
108 public static void main(String args[]) {
109 // Avoid string concatenation
110 System.out.print(actualMsg);
111 System.out.println(Runtime.getRuntime().maxMemory());
112 }
113 }