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