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/*
* Copyright (c) 2004, Oracle and/or its affiliates. All rights reserved.
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
*
* This code is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License version 2 only, as
* published by the Free Software Foundation.
*
* This code is distributed in the hope that it will be useful, but WITHOUT
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
* version 2 for more details (a copy is included in the LICENSE file that
* accompanied this code).
*
* You should have received a copy of the GNU General Public License version
* 2 along with this work; if not, write to the Free Software Foundation,
* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
*
* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
* or visit www.oracle.com if you need additional information or have any
* questions.
*/
// See bug 5094825 / ClassLoadDeadlock.sh
import java.net.*;
import java.security.*;
public class ClassLoaderDeadlock {
public static void main(String[] args) throws Exception {
// create a new classloader
URL url = new URL("file:provider/");
final DelayClassLoader cl = new DelayClassLoader(url);
// install a provider on the custom class loader as the most prefered provider
Class clazz = cl.loadClass("HashProvider");
Provider p = (Provider)clazz.newInstance();
Security.insertProviderAt(p, 1);
// add a delay in class loading for reproducability
cl.delay = 1000;
new Thread() {
public void run() {
try {
// load a random system class
// this locks the DelayClassLoader and after the delay the system class loader
Class c1 = cl.loadClass("java.lang.String");
System.out.println(c1);
} catch (Exception e) {
e.printStackTrace();
}
}
}.start();
// make sure the other thread got a chance to run and grab the lock
Thread.sleep(200);
// load a random class from a signed JAR file to trigger JAR signature verification
// locks system class loader first and then tries to lock DelayClassLoader to load the hashes
// DEADLOCK HAPPENS HERE
Class c2 = Class.forName("com.abc.Tst1");
// NOT REACHED
System.out.println(c2);
System.out.println("OK");
}
static class DelayClassLoader extends URLClassLoader {
volatile int delay;
DelayClassLoader(URL url) {
super(new URL[] {url});
}
protected synchronized Class loadClass(String name, boolean resolve) throws ClassNotFoundException {
System.out.println("-loadClass(" + name + "," + resolve + ")");
try {
// delay so that we hold the lock for a longer period
// makes it much easier to reproduce
Thread.sleep(delay);
} catch (InterruptedException e) { e.printStackTrace(); }
return super.loadClass(name, resolve);
}
}
}
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