1 /*
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3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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5 * This code is free software; you can redistribute it and/or modify it
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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 /* @test
25 * @bug 6482247
26 * @summary Test that creating MXBeans does not introduce memory leaks.
27 * @author Eamonn McManus
28 *
29 * @run build LeakTest RandomMXBeanTest MerlinMXBean TigerMXBean
30 * @run main LeakTest
31 */
32
33 /* In this test we create a ClassLoader, then use it to load and run another
34 * jtreg test. When the other test has completed, we wait for the ClassLoader
35 * to be garbage-collected. If it has not been gc'd after a reasonable
36 * amount of time, then something is keeping a reference to the ClassLoader,
37 * which implies a memory leak.
38 *
39 * This test can be applied to any jtreg test, not just the MXBean tests.
40 */
41
42 import java.io.File;
43 import java.lang.ref.Reference;
44 import java.lang.ref.ReferenceQueue;
45 import java.lang.ref.WeakReference;
46 import java.lang.reflect.Method;
47 import java.net.URL;
48 import java.net.URLClassLoader;
49 import java.nio.file.Paths;
50
51 public class LeakTest {
52 /* Ideally we would include MXBeanTest in the list of tests, since it
53 * has fairly complete coverage. However, the ClassLoader fails to be
54 * gc'd when we do that, and I am unable to figure out why. Examining
55 * a heap dump shows only weak references to the ClassLoader. I suspect
56 * something is wrong in the internals of the reflection classes, used
57 * quite heavily by MXBeanTest.
58 */
59 // private static Class<?>[] otherTests = {MXBeanTest.class};
60
61 private static Class<?>[] otherTests = {RandomMXBeanTest.class};
62
63 // This class just makes it easier for us to spot our loader in heap dumps
64 private static class ShadowClassLoader extends URLClassLoader {
65 ShadowClassLoader(URL[] urls, ClassLoader parent) {
66 super(urls, parent);
67 }
68 }
69
70 public static void main(String[] args) throws Exception {
71 System.out.println("Testing that no references are held to ClassLoaders " +
72 "by caches in the MXBean infrastructure");
73 for (Class<?> testClass : otherTests)
74 test(testClass);
75 if (failure != null)
76 throw new Exception("CLASSLOADER LEAK TEST FAILED: " + failure);
77 System.out.println("CLASSLOADER LEAK TEST PASSED");
78 if (args.length > 0) {
79 System.out.println("Waiting for input");
80 System.in.read();
81 }
82 }
83
84 private static void test(Class<?> originalTestClass) throws Exception {
85 System.out.println();
86 System.out.println("TESTING " + originalTestClass.getName());
87 WeakReference<ClassLoader> wr = testShadow(originalTestClass);
88 System.out.println("Test passed, waiting for ClassLoader to disappear");
89 long deadline = System.currentTimeMillis() + 20*1000;
90 Reference<? extends ClassLoader> ref;
91 while (wr.get() != null && System.currentTimeMillis() < deadline) {
92 System.gc();
93 Thread.sleep(100);
94 }
95 if (wr.get() != null)
96 fail(originalTestClass.getName() + " kept ClassLoader reference");
97 }
98
99 private static WeakReference<ClassLoader>
100 testShadow(Class<?> originalTestClass) throws Exception {
101 String[] cpaths = System.getProperty("test.classes", ".")
102 .split(File.pathSeparator);
103 URL[] urls = new URL[cpaths.length];
104 for (int i=0; i < cpaths.length; i++) {
105 urls[i] = Paths.get(cpaths[i]).toUri().toURL();
106 }
107
108 URLClassLoader shadowLoader =
109 new ShadowClassLoader(urls, originalTestClass.getClassLoader().getParent());
110 System.out.println("Shadow loader is " + shadowLoader);
111 String className = originalTestClass.getName();
112 Class<?> testClass = Class.forName(className, false, shadowLoader);
113 if (testClass.getClassLoader() != shadowLoader) {
114 throw new IllegalArgumentException("Loader didn't work: " +
115 testClass.getClassLoader() + " != " + shadowLoader);
116 }
117 Method main = testClass.getMethod("main", String[].class);
118 main.invoke(null, (Object) new String[0]);
119 return new WeakReference<ClassLoader>(shadowLoader);
120 }
121
122 private static void fail(String why) {
123 System.out.println("FAILED: " + why);
124 failure = why;
125 }
126
127 private static String failure;
128 }