RuntimeThreadInheritanceLeak.java revision 169:fa4df2d26d9b 
1/*
2 * Copyright 2001-2003 Sun Microsystems, Inc.  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 Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
20 * CA 95054 USA or visit www.sun.com if you need additional information or
21 * have any questions.
22 */
23
24/* @test
25 * @bug 4404702
26 * @summary When the RMI runtime (lazily) spawns system threads that could
27 * outlive the application context in which they were (happened to be)
28 * created, such threads should not inherit (thread local) data specific to
29 * such an application context for various isolation reasons (see 4219095).
30 * While there is not yet a practical means for a general solution to this
31 * problem, the particular problem documented in 4404702-- the inheritance
32 * of the parent thread's context class loader, preventing that loader from
33 * being garbage collected in the future-- can be easily fixed.  This test
34 * verifies that the context class loader in effect when the first remote
35 * object is exported (and thus when some long-lived RMI daemon threads are
36 * created) can be garbage collected after the remote object has been
37 * unexported.  [Note that this test is somewhat at the mercy of other J2SE
38 * subsystems also not holding on to the loader in their daemon threads.]
39 * @author Peter Jones
40 *
41 * @build RuntimeThreadInheritanceLeak
42 * @build RuntimeThreadInheritanceLeak_Stub
43 * @run main/othervm RuntimeThreadInheritanceLeak
44 */
45
46import java.lang.ref.Reference;
47import java.lang.ref.ReferenceQueue;
48import java.lang.ref.WeakReference;
49import java.net.URL;
50import java.net.URLClassLoader;
51import java.rmi.Remote;
52import java.rmi.RemoteException;
53import java.rmi.server.UnicastRemoteObject;
54import java.util.Iterator;
55import java.util.Map;
56
57public class RuntimeThreadInheritanceLeak implements Remote {
58
59    private static final int TIMEOUT = 20000;
60
61    public static void main(String[] args) {
62
63        System.err.println("\nRegression test for bug 4404702\n");
64
65        /*
66         * HACK: Work around the fact that java.util.logging.LogManager's
67         * (singleton) construction also has this bug-- it will register a
68         * "shutdown hook", i.e. a thread, which will inherit and pin the
69         * current thread's context class loader for the lifetime of the VM--
70         * by causing the LogManager to be initialized now, instead of by
71         * RMI when our special context class loader is set.
72         */
73        java.util.logging.LogManager.getLogManager();
74
75        /*
76         * HACK: Work around the fact that the non-native, thread-based
77         * SecureRandom seed generator (ThreadedSeedGenerator) seems to
78         * have this bug too (which had been causing this test to fail
79         * when run with jtreg on Windows XP-- see 4910382).
80         */
81        (new java.security.SecureRandom()).nextInt();
82
83        RuntimeThreadInheritanceLeak obj = new RuntimeThreadInheritanceLeak();
84
85        try {
86            ClassLoader loader = URLClassLoader.newInstance(new URL[0]);
87            ReferenceQueue refQueue = new ReferenceQueue();
88            Reference loaderRef = new WeakReference(loader, refQueue);
89            System.err.println("created loader: " + loader);
90
91            Thread.currentThread().setContextClassLoader(loader);
92            UnicastRemoteObject.exportObject(obj);
93            Thread.currentThread().setContextClassLoader(
94                ClassLoader.getSystemClassLoader());
95            System.err.println(
96                "exported remote object with loader as context class loader");
97
98            loader = null;
99            System.err.println("nulled strong reference to loader");
100
101            UnicastRemoteObject.unexportObject(obj, true);
102            System.err.println("unexported remote object");
103
104            /*
105             * HACK: Work around the fact that the sun.misc.GC daemon thread
106             * also has this bug-- it will have inherited our loader as its
107             * context class loader-- by giving it a chance to pass away.
108             */
109            Thread.sleep(2000);
110            System.gc();
111
112            System.err.println(
113                "waiting to be notified of loader being weakly reachable...");
114            Reference dequeued = refQueue.remove(TIMEOUT);
115            if (dequeued == null) {
116                System.err.println(
117                    "TEST FAILED: loader not deteced weakly reachable");
118                dumpThreads();
119                throw new RuntimeException(
120                    "TEST FAILED: loader not detected weakly reachable");
121            }
122
123            System.err.println(
124                "TEST PASSED: loader detected weakly reachable");
125            dumpThreads();
126
127        } catch (RuntimeException e) {
128            throw e;
129        } catch (Exception e) {
130            throw new RuntimeException("TEST FAILED: unexpected exception", e);
131        } finally {
132            try {
133                UnicastRemoteObject.unexportObject(obj, true);
134            } catch (RemoteException e) {
135            }
136        }
137    }
138
139    /**
140     * Dumps information about all live threads to System.err,
141     * including their context class loaders.
142     **/
143    private static void dumpThreads() {
144        System.err.println(
145            "current live threads and their context class loaders:");
146        Map threads = Thread.getAllStackTraces();
147        for (Iterator iter = threads.entrySet().iterator(); iter.hasNext();) {
148            Map.Entry e = (Map.Entry) iter.next();
149            Thread t = (Thread) e.getKey();
150            System.err.println("  thread: " + t);
151            System.err.println("  context class loader: " +
152                               t.getContextClassLoader());
153            StackTraceElement[] trace = (StackTraceElement[]) e.getValue();
154            for (int i = 0; i < trace.length; i++) {
155                System.err.println("    " + trace[i]);
156            }
157        }
158    }
159}
160