1 /* 2 * Copyright (c) 2006, 2008, 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 /* @test 25 * @bug 6482247 26 * @summary Test that creating MXBeans does not introduce memory leaks. 27 * @author Eamonn McManus 28 * @run build LeakTest RandomMXBeanTest 29 * @run main LeakTest 30 */ 31 32 /* In this test we create a ClassLoader, then use it to load and run another 33 * jtreg test. When the other test has completed, we wait for the ClassLoader 34 * to be garbage-collected. If it has not been gc'd after a reasonable 35 * amount of time, then something is keeping a reference to the ClassLoader, 36 * which implies a memory leak. 37 * 38 * This test can be applied to any jtreg test, not just the MXBean tests. 39 */ 40 41 import java.lang.ref.Reference; 42 import java.lang.ref.ReferenceQueue; 43 import java.lang.ref.WeakReference; 44 import java.lang.reflect.Method; 45 import java.net.URL; 46 import java.net.URLClassLoader; 47 48 public class LeakTest { 49 /* Ideally we would include MXBeanTest in the list of tests, since it 50 * has fairly complete coverage. However, the ClassLoader fails to be 51 * gc'd when we do that, and I am unable to figure out why. Examining 52 * a heap dump shows only weak references to the ClassLoader. I suspect 53 * something is wrong in the internals of the reflection classes, used 54 * quite heavily by MXBeanTest. 55 */ 56 // private static Class<?>[] otherTests = {MXBeanTest.class}; 57 58 private static Class<?>[] otherTests = {RandomMXBeanTest.class}; 59 60 // This class just makes it easier for us to spot our loader in heap dumps 61 private static class ShadowClassLoader extends URLClassLoader { 62 ShadowClassLoader(URL[] urls, ClassLoader parent) { 63 super(urls, parent); 64 } 65 } 66 67 public static void main(String[] args) throws Exception { 68 System.out.println("Testing that no references are held to ClassLoaders " + 69 "by caches in the MXBean infrastructure"); 70 for (Class<?> testClass : otherTests) 71 test(testClass); 72 if (failure != null) 73 throw new Exception("CLASSLOADER LEAK TEST FAILED: " + failure); 74 System.out.println("CLASSLOADER LEAK TEST PASSED"); 75 if (args.length > 0) { 76 System.out.println("Waiting for input"); 77 System.in.read(); 78 } 79 } 80 81 private static void test(Class<?> originalTestClass) throws Exception { 82 System.out.println(); 83 System.out.println("TESTING " + originalTestClass.getName()); 84 WeakReference<ClassLoader> wr = testShadow(originalTestClass); 85 System.out.println("Test passed, waiting for ClassLoader to disappear"); 86 long deadline = System.currentTimeMillis() + 20*1000; 87 Reference<? extends ClassLoader> ref; 88 while (wr.get() != null && System.currentTimeMillis() < deadline) { 89 System.gc(); 90 Thread.sleep(100); 91 } 92 if (wr.get() != null) 93 fail(originalTestClass.getName() + " kept ClassLoader reference"); 94 } 95 96 private static WeakReference<ClassLoader> 97 testShadow(Class<?> originalTestClass) throws Exception { 98 URLClassLoader originalLoader = 99 (URLClassLoader) originalTestClass.getClassLoader(); 100 URL[] urls = originalLoader.getURLs(); 101 URLClassLoader shadowLoader = 102 new ShadowClassLoader(urls, originalLoader.getParent()); 103 System.out.println("Shadow loader is " + shadowLoader); 104 String className = originalTestClass.getName(); 105 Class<?> testClass = Class.forName(className, false, shadowLoader); 106 if (testClass.getClassLoader() != shadowLoader) { 107 throw new IllegalArgumentException("Loader didn't work: " + 108 testClass.getClassLoader() + " != " + shadowLoader); 109 } 110 Method main = testClass.getMethod("main", String[].class); 111 main.invoke(null, (Object) new String[0]); 112 return new WeakReference<ClassLoader>(shadowLoader); 113 } 114 115 private static void fail(String why) { 116 System.out.println("FAILED: " + why); 117 failure = why; 118 } 119 120 private static String failure; 121 }