129 lines
4.7 KiB
Java
129 lines
4.7 KiB
Java
/*
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* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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*
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* This code is free software; you can redistribute it and/or modify it
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* under the terms of the GNU General Public License version 2 only, as
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* published by the Free Software Foundation.
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*
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* This code is distributed in the hope that it will be useful, but WITHOUT
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* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
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* version 2 for more details (a copy is included in the LICENSE file that
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* accompanied this code).
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*
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* You should have received a copy of the GNU General Public License version
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* 2 along with this work; if not, write to the Free Software Foundation,
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* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
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*
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* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
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* or visit www.oracle.com if you need additional information or have any
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* questions.
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*/
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/*
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* This file is available under and governed by the GNU General Public
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* License version 2 only, as published by the Free Software Foundation.
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* However, the following notice accompanied the original version of this
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* file:
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*
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* Written by Martin Buchholz with assistance from members of JCP
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* JSR-166 Expert Group and released to the public domain, as
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* explained at http://creativecommons.org/publicdomain/zero/1.0/
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*/
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/*
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* @test
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* @bug 8074773
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* @summary Stress test looks for lost unparks
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*/
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import static java.util.concurrent.TimeUnit.SECONDS;
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import java.util.SplittableRandom;
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import java.util.concurrent.CountDownLatch;
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import java.util.concurrent.ExecutorService;
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import java.util.concurrent.Executors;
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import java.util.concurrent.atomic.AtomicReferenceArray;
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import java.util.concurrent.locks.LockSupport;
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public final class ParkLoops {
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static final int THREADS = 4;
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static final int ITERS = 30_000;
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static class Parker implements Runnable {
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static {
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// Reduce the risk of rare disastrous classloading in first call to
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// LockSupport.park: https://bugs.openjdk.java.net/browse/JDK-8074773
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Class<?> ensureLoaded = LockSupport.class;
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}
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private final AtomicReferenceArray<Thread> threads;
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private final CountDownLatch done;
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private final SplittableRandom rnd;
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Parker(AtomicReferenceArray<Thread> threads,
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CountDownLatch done,
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SplittableRandom rnd) {
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this.threads = threads; this.done = done; this.rnd = rnd;
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}
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public void run() {
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final Thread current = Thread.currentThread();
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for (int k = ITERS, j; k > 0; k--) {
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do {
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j = rnd.nextInt(THREADS);
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} while (!threads.compareAndSet(j, null, current));
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do { // handle spurious wakeups
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LockSupport.park();
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} while (threads.get(j) == current);
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}
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done.countDown();
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}
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}
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static class Unparker implements Runnable {
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static {
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// Reduce the risk of rare disastrous classloading in first call to
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// LockSupport.park: https://bugs.openjdk.java.net/browse/JDK-8074773
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Class<?> ensureLoaded = LockSupport.class;
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}
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private final AtomicReferenceArray<Thread> threads;
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private final CountDownLatch done;
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private final SplittableRandom rnd;
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Unparker(AtomicReferenceArray<Thread> threads,
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CountDownLatch done,
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SplittableRandom rnd) {
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this.threads = threads; this.done = done; this.rnd = rnd;
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}
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public void run() {
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for (int n = 0; (n++ & 0xff) != 0 || done.getCount() > 0;) {
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int j = rnd.nextInt(THREADS);
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Thread parker = threads.get(j);
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if (parker != null &&
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threads.compareAndSet(j, parker, null)) {
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LockSupport.unpark(parker);
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}
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}
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}
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}
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public static void main(String[] args) throws Exception {
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final SplittableRandom rnd = new SplittableRandom();
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final ExecutorService pool = Executors.newCachedThreadPool();
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final AtomicReferenceArray<Thread> threads
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= new AtomicReferenceArray<>(THREADS);
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final CountDownLatch done = new CountDownLatch(THREADS);
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for (int i = 0; i < THREADS; i++) {
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pool.submit(new Parker(threads, done, rnd.split()));
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pool.submit(new Unparker(threads, done, rnd.split()));
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}
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// Let test harness handle timeout
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done.await();
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pool.shutdown();
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pool.awaitTermination(Long.MAX_VALUE, SECONDS);
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}
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}
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