| /* |
| * 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. |
| */ |
| |
| /* |
| * This file is available under and governed by the GNU General Public |
| * License version 2 only, as published by the Free Software Foundation. |
| * However, the following notice accompanied the original version of this |
| * file: |
| * |
| * Written by Martin Buchholz with assistance from members of JCP |
| * JSR-166 Expert Group and released to the public domain, as |
| * explained at http://creativecommons.org/publicdomain/zero/1.0/ |
| */ |
| |
| /* |
| * @test |
| * @bug 8074773 |
| * @summary Stress test looks for lost unparks |
| */ |
| |
| import static java.util.concurrent.TimeUnit.SECONDS; |
| |
| import java.util.SplittableRandom; |
| import java.util.concurrent.CountDownLatch; |
| import java.util.concurrent.ExecutorService; |
| import java.util.concurrent.Executors; |
| import java.util.concurrent.atomic.AtomicReferenceArray; |
| import java.util.concurrent.locks.LockSupport; |
| |
| public final class ParkLoops { |
| static final int THREADS = 4; |
| static final int ITERS = 30_000; |
| |
| static class Parker implements Runnable { |
| static { |
| // Reduce the risk of rare disastrous classloading in first call to |
| // LockSupport.park: https://bugs.openjdk.java.net/browse/JDK-8074773 |
| Class<?> ensureLoaded = LockSupport.class; |
| } |
| |
| private final AtomicReferenceArray<Thread> threads; |
| private final CountDownLatch done; |
| private final SplittableRandom rnd; |
| |
| Parker(AtomicReferenceArray<Thread> threads, |
| CountDownLatch done, |
| SplittableRandom rnd) { |
| this.threads = threads; this.done = done; this.rnd = rnd; |
| } |
| |
| public void run() { |
| final Thread current = Thread.currentThread(); |
| for (int k = ITERS, j; k > 0; k--) { |
| do { |
| j = rnd.nextInt(THREADS); |
| } while (!threads.compareAndSet(j, null, current)); |
| do { // handle spurious wakeups |
| LockSupport.park(); |
| } while (threads.get(j) == current); |
| } |
| done.countDown(); |
| } |
| } |
| |
| static class Unparker implements Runnable { |
| static { |
| // Reduce the risk of rare disastrous classloading in first call to |
| // LockSupport.park: https://bugs.openjdk.java.net/browse/JDK-8074773 |
| Class<?> ensureLoaded = LockSupport.class; |
| } |
| |
| private final AtomicReferenceArray<Thread> threads; |
| private final CountDownLatch done; |
| private final SplittableRandom rnd; |
| |
| Unparker(AtomicReferenceArray<Thread> threads, |
| CountDownLatch done, |
| SplittableRandom rnd) { |
| this.threads = threads; this.done = done; this.rnd = rnd; |
| } |
| |
| public void run() { |
| for (int n = 0; (n++ & 0xff) != 0 || done.getCount() > 0;) { |
| int j = rnd.nextInt(THREADS); |
| Thread parker = threads.get(j); |
| if (parker != null && |
| threads.compareAndSet(j, parker, null)) { |
| LockSupport.unpark(parker); |
| } |
| } |
| } |
| } |
| |
| public static void main(String[] args) throws Exception { |
| final SplittableRandom rnd = new SplittableRandom(); |
| final ExecutorService pool = Executors.newCachedThreadPool(); |
| final AtomicReferenceArray<Thread> threads |
| = new AtomicReferenceArray<>(THREADS); |
| final CountDownLatch done = new CountDownLatch(THREADS); |
| for (int i = 0; i < THREADS; i++) { |
| pool.submit(new Parker(threads, done, rnd.split())); |
| pool.submit(new Unparker(threads, done, rnd.split())); |
| } |
| // Let test harness handle timeout |
| done.await(); |
| pool.shutdown(); |
| pool.awaitTermination(Long.MAX_VALUE, SECONDS); |
| } |
| } |