1/*
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3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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7 * published by the Free Software Foundation.
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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
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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
42import java.io.File;
43import java.lang.ref.Reference;
44import java.lang.ref.ReferenceQueue;
45import java.lang.ref.WeakReference;
46import java.lang.reflect.Method;
47import java.net.URL;
48import java.net.URLClassLoader;
49import java.nio.file.Paths;
50
51public 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}
129