1/*
2 * Copyright (c) 2004, 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// See bug 5094825 / ClassLoadDeadlock.sh
25
26import java.net.*;
27
28import java.security.*;
29
30public class ClassLoaderDeadlock {
31
32    public static void main(String[] args) throws Exception {
33        // create a new classloader
34        URL url = new URL("file:provider/");
35        final DelayClassLoader cl = new DelayClassLoader(url);
36
37        // install a provider on the custom class loader as the most prefered provider
38        Class clazz = cl.loadClass("HashProvider");
39        Provider p = (Provider)clazz.newInstance();
40        Security.insertProviderAt(p, 1);
41
42        // add a delay in class loading for reproducability
43        cl.delay = 1000;
44
45        new Thread() {
46            public void run() {
47                try {
48                    // load a random system class
49                    // this locks the DelayClassLoader and after the delay the system class loader
50                    Class c1 = cl.loadClass("java.lang.String");
51                    System.out.println(c1);
52                } catch (Exception e) {
53                    e.printStackTrace();
54                }
55            }
56        }.start();
57
58        // make sure the other thread got a chance to run and grab the lock
59        Thread.sleep(200);
60
61        // load a random class from a signed JAR file to trigger JAR signature verification
62        // locks system class loader first and then tries to lock DelayClassLoader to load the hashes
63        // DEADLOCK HAPPENS HERE
64        Class c2 = Class.forName("com.abc.Tst1");
65
66        // NOT REACHED
67        System.out.println(c2);
68
69        System.out.println("OK");
70    }
71
72    static class DelayClassLoader extends URLClassLoader {
73
74        volatile int delay;
75
76        DelayClassLoader(URL url) {
77            super(new URL[] {url});
78        }
79
80        protected synchronized Class loadClass(String name, boolean resolve) throws ClassNotFoundException {
81            System.out.println("-loadClass(" + name + "," + resolve + ")");
82            try {
83                // delay so that we hold the lock for a longer period
84                // makes it much easier to reproduce
85                Thread.sleep(delay);
86            } catch (InterruptedException e) { e.printStackTrace(); }
87            return super.loadClass(name, resolve);
88        }
89    }
90
91}
92