ClassForNameLeak.java

/*
 * Copyright (c) 2016, 2018, 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.
 */

/*
 * @test
 * @bug 8151486
 * @summary Call Class.forName() on the system classloader from a class loaded
 *          from a custom classloader.
 * @library /lib/testlibrary
 * @build jdk.testlibrary.Utils jdk.testlibrary.JarUtils
 * @build ClassForName ClassForNameLeak
 * @run main/othervm/policy=test.policy -Djava.security.manager ClassForNameLeak
 */

import java.io.IOException;
import java.lang.ref.PhantomReference;
import java.lang.ref.Reference;
import java.lang.ref.ReferenceQueue;
import java.net.MalformedURLException;
import java.net.URL;
import java.net.URLClassLoader;
import java.nio.file.Path;
import java.nio.file.Paths;
import java.util.List;
import java.util.concurrent.Callable;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.Future;
import java.util.stream.Collectors;
import java.util.stream.Stream;
import jdk.testlibrary.Utils;
import jdk.testlibrary.JarUtils;

/*
 * Create .jar, load ClassForName from .jar using a URLClassLoader
 */
public class ClassForNameLeak {
    private static final long TIMEOUT = (long)(5000.0 * Utils.TIMEOUT_FACTOR);
    private static final int THREADS = 10;
    private static final Path jarFilePath = Paths.get("cfn.jar");
    private static final ReferenceQueue<ClassLoader> rq = new ReferenceQueue<>();

    static class TestLoader {
        private final PhantomReference<ClassLoader> ref;

        TestLoader() {
            this.ref = loadAndRun();
        }

        // Use a new classloader to load the ClassForName class, then run its
        // Runnable.
        PhantomReference<ClassLoader> loadAndRun() {
            try {
                ClassLoader classLoader =
                    new URLClassLoader(new URL[]{jarFilePath.toUri().toURL()},
                        ClassLoader.getSystemClassLoader());

                Class<?> loadClass = Class.forName("ClassForName", true, classLoader);
                ((Runnable) loadClass.newInstance()).run();

                return new PhantomReference<>(classLoader, rq);
            } catch (MalformedURLException | ReflectiveOperationException e) {
                throw new RuntimeException(e);
            }
        }

        PhantomReference<ClassLoader> getRef() {
            return ref;
        }
    }

    public static void main(String... args) throws Exception {
        // create the JAR file
        setup();

        // Make simultaneous calls to the test method, to stress things a bit
        ExecutorService es = Executors.newFixedThreadPool(THREADS);

        List<Callable<TestLoader>> callables =
                Stream.generate(() -> {
                    Callable<TestLoader> cprcl = TestLoader::new;
                    return cprcl;
                }).limit(THREADS).collect(Collectors.toList());

        List<Future<TestLoader>> futures = es.invokeAll(callables);

        // Give the GC a chance to enqueue the PhantomReferences
        for (int i = 0; i < 10; i++) {
            System.gc();
        }

        // Make sure all PhantomReferences to the leaked classloader are enqueued
        for (int j = 0; j < futures.size(); j++) {
            Reference rmRef = rq.remove(TIMEOUT);
            if (rmRef == null) {
                throw new RuntimeException("ClassLoader was never enqueued!");
            } else {
                System.out.println("Enqueued " + rmRef);
            }
        }
        es.shutdown();
        System.out.println("All ClassLoaders successfully enqueued");
    }

    private static final String CLASSFILENAME = "ClassForName.class";
    private static void setup() throws IOException {
        String testclasses = System.getProperty("test.classes", ".");

        // Create a temporary .jar file containing ClassForName.class
        Path testClassesDir = Paths.get(testclasses);
        JarUtils.createJar(jarFilePath.toString(), testClassesDir.toString(), CLASSFILENAME);
    }
}