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 /test/lib
30 * @modules java.base/jdk.internal.misc
31 * @build sun.hotspot.WhiteBox
32 * @run main ClassFileInstaller sun.hotspot.WhiteBox
33 * @run main/othervm -Xbootclasspath/a:. -XX:+UnlockDiagnosticVMOptions -XX:+WhiteBoxAPI TestSmallHeap
34 */
35
36 /* Note: It would be nice to verify the minimal supported heap size here,
37 * but we align the heap size based on the card table size. And the card table
38 * size is aligned based on the minimal pages size provided by the os. This
39 * means that on most platforms, where the minimal page size is 4k, we get a
40 * minimal heap size of 2m but on Solaris/Sparc we have a page size of 8k and
41 * get a minimal heap size of 4m. And on platforms where the page size is 64k
42 * we get a minimal heap size of 32m. We never use large pages for the card table.
43 *
44 * There is also no check in the VM for verifying that the maximum heap size
45 * is larger than the supported minimal heap size.
46 *
47 * To work around these behaviors this test uses -Xmx4m but then
48 * calculates what the expected heap size should be. The calculation is a
49 * simplified version of the code in the VM. We assume that the card table will
50 * use one page. Each byte in the card table corresponds to 512 bytes on the heap.
51 * So, the expected heap size is page_size * 512.
52 *
53 * There is no formal requirement for the minimal value of the maximum heap size
54 * the VM should support. In most cases the VM could start with -Xmx2m.
55 * But with 2m limit GC could be triggered before VM initialization completed.
56 * Therefore we start the VM with 4M heap.
57 */
58
59 import jdk.test.lib.Asserts;
60 import jdk.test.lib.process.OutputAnalyzer;
61 import jdk.test.lib.process.ProcessTools;
62
63 import java.util.LinkedList;
64
65 import sun.hotspot.WhiteBox;
66
67 public class TestSmallHeap {
68
69 public static void main(String[] args) throws Exception {
70 // Do all work in the VM driving the test, the VM
71 // with the small heap size should do as little as
72 // possible to avoid hitting an OOME.
73 WhiteBox wb = WhiteBox.getWhiteBox();
74 int pageSize = wb.getVMPageSize();
75 int heapBytesPerCard = 512;
76 long expectedMaxHeap = pageSize * heapBytesPerCard;
77
78 verifySmallHeapSize("-XX:+UseParallelGC", expectedMaxHeap);
79 verifySmallHeapSize("-XX:+UseSerialGC", expectedMaxHeap);
80 verifySmallHeapSize("-XX:+UseG1GC", expectedMaxHeap);
81 verifySmallHeapSize("-XX:+UseConcMarkSweepGC", expectedMaxHeap);
82 }
83
84 private static void verifySmallHeapSize(String gc, long expectedMaxHeap) throws Exception {
85 long minMaxHeap = 4 * 1024 * 1024;
86 LinkedList<String> vmOptions = new LinkedList<>();
87 vmOptions.add(gc);
88 vmOptions.add("-Xmx" + minMaxHeap);
89 vmOptions.add("-XX:+PrintFlagsFinal");
90 vmOptions.add(VerifyHeapSize.class.getName());
91
92 ProcessBuilder pb = ProcessTools.createJavaProcessBuilder(vmOptions.toArray(new String[0]));
93 OutputAnalyzer analyzer = new OutputAnalyzer(pb.start());
94 analyzer.shouldHaveExitValue(0);
95
96 expectedMaxHeap = Math.max(expectedMaxHeap, minMaxHeap);
97 long maxHeapSize = Long.parseLong(analyzer.firstMatch("MaxHeapSize.+=\\s+(\\d+)",1));
98 long actualHeapSize = Long.parseLong(analyzer.firstMatch(VerifyHeapSize.actualMsg + "(\\d+)",1));
99 Asserts.assertEQ(maxHeapSize, expectedMaxHeap);
100 Asserts.assertLessThanOrEqual(actualHeapSize, maxHeapSize);
101 }
102 }
103
104 class VerifyHeapSize {
105 public static final String actualMsg = "Actual heap size: ";
106
107 public static void main(String args[]) {
108 // Avoid string concatenation
109 System.out.print(actualMsg);
110 System.out.println(Runtime.getRuntime().maxMemory());
111 }
112 }