100 lines
3.4 KiB
Java
100 lines
3.4 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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* @test
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* @bug 8023234
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* @summary StampedLock serializes readers on writer unlock
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* @author Dmitry Chyuko
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* @author Aleksey Shipilev
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*/
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import java.util.concurrent.CyclicBarrier;
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import java.util.concurrent.atomic.AtomicReference;
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import java.util.concurrent.locks.StampedLock;
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public class ReadersUnlockAfterWriteUnlock {
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public static void main(String[] args) throws InterruptedException {
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final int RNUM = 2;
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final int REPS = 128;
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final StampedLock sl = new StampedLock();
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final AtomicReference<Throwable> bad = new AtomicReference<>();
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final CyclicBarrier iterationStart = new CyclicBarrier(RNUM + 1);
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final CyclicBarrier readersHaveLocks = new CyclicBarrier(RNUM);
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final CyclicBarrier writerHasLock = new CyclicBarrier(RNUM + 1);
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Runnable reader = () -> {
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try {
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for (int i = 0; i < REPS; i++) {
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iterationStart.await();
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writerHasLock.await();
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long rs = sl.readLock();
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// single reader blocks here indefinitely if readers
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// are serialized
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readersHaveLocks.await();
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sl.unlockRead(rs);
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}
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} catch (Throwable ex) {
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ex.printStackTrace();
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bad.set(ex);
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}
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};
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Thread[] threads = new Thread[RNUM];
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for (int i = 0 ; i < RNUM; i++) {
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Thread thread = new Thread(reader, "Reader");
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threads[i] = thread;
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thread.start();
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}
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for (int i = 0; i < REPS; i++) {
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try {
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iterationStart.await();
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long ws = sl.writeLock();
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writerHasLock.await();
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awaitWaitState(threads);
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sl.unlockWrite(ws);
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} catch (Exception e) {
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throw new IllegalStateException(e);
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}
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}
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for (Thread thread : threads)
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thread.join();
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if (bad.get() != null)
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throw new AssertionError(bad.get());
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}
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static void awaitWaitState(Thread[] threads) {
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restart: for (;;) {
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for (Thread thread : threads) {
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if (thread.getState() != Thread.State.WAITING) {
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Thread.yield();
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continue restart;
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}
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}
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break;
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}
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}
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}
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