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