| /* |
| * Copyright (c) 2004, 2005, Oracle and/or its affiliates. All rights reserved. |
| * |
| * Redistribution and use in source and binary forms, with or without |
| * modification, are permitted provided that the following conditions |
| * are met: |
| * |
| * - Redistributions of source code must retain the above copyright |
| * notice, this list of conditions and the following disclaimer. |
| * |
| * - Redistributions in binary form must reproduce the above copyright |
| * notice, this list of conditions and the following disclaimer in the |
| * documentation and/or other materials provided with the distribution. |
| * |
| * - Neither the name of Oracle nor the names of its |
| * contributors may be used to endorse or promote products derived |
| * from this software without specific prior written permission. |
| * |
| * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS |
| * IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, |
| * THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR |
| * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR |
| * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, |
| * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, |
| * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR |
| * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF |
| * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING |
| * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS |
| * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. |
| */ |
| |
| /* |
| */ |
| |
| import java.util.concurrent.CyclicBarrier; |
| import java.util.concurrent.BrokenBarrierException; |
| import java.util.concurrent.locks.Lock; |
| import java.util.concurrent.locks.ReentrantLock; |
| import java.io.IOException; |
| |
| /** |
| * This Deadlock class demonstrates the capability of performing |
| * deadlock detection programmatically within the application using |
| * the java.lang.management API. |
| * |
| * See ThreadMonitor.java for the use of java.lang.management.ThreadMXBean |
| * API. |
| */ |
| public class Deadlock { |
| public static void main(String[] argv) { |
| Deadlock dl = new Deadlock(); |
| |
| // Now find deadlock |
| ThreadMonitor monitor = new ThreadMonitor(); |
| boolean found = false; |
| while (!found) { |
| found = monitor.findDeadlock(); |
| try { |
| Thread.sleep(500); |
| } catch (InterruptedException e) { |
| System.exit(1); |
| } |
| } |
| |
| System.out.println("\nPress <Enter> to exit this Deadlock program.\n"); |
| waitForEnterPressed(); |
| } |
| |
| |
| private CyclicBarrier barrier = new CyclicBarrier(6); |
| public Deadlock() { |
| DeadlockThread[] dThreads = new DeadlockThread[6]; |
| |
| Monitor a = new Monitor("a"); |
| Monitor b = new Monitor("b"); |
| Monitor c = new Monitor("c"); |
| dThreads[0] = new DeadlockThread("MThread-1", a, b); |
| dThreads[1] = new DeadlockThread("MThread-2", b, c); |
| dThreads[2] = new DeadlockThread("MThread-3", c, a); |
| |
| Lock d = new ReentrantLock(); |
| Lock e = new ReentrantLock(); |
| Lock f = new ReentrantLock(); |
| |
| dThreads[3] = new DeadlockThread("SThread-4", d, e); |
| dThreads[4] = new DeadlockThread("SThread-5", e, f); |
| dThreads[5] = new DeadlockThread("SThread-6", f, d); |
| |
| // make them daemon threads so that the test will exit |
| for (int i = 0; i < 6; i++) { |
| dThreads[i].setDaemon(true); |
| dThreads[i].start(); |
| } |
| } |
| |
| class DeadlockThread extends Thread { |
| private Lock lock1 = null; |
| private Lock lock2 = null; |
| private Monitor mon1 = null; |
| private Monitor mon2 = null; |
| private boolean useSync; |
| |
| DeadlockThread(String name, Lock lock1, Lock lock2) { |
| super(name); |
| this.lock1 = lock1; |
| this.lock2 = lock2; |
| this.useSync = true; |
| } |
| DeadlockThread(String name, Monitor mon1, Monitor mon2) { |
| super(name); |
| this.mon1 = mon1; |
| this.mon2 = mon2; |
| this.useSync = false; |
| } |
| public void run() { |
| if (useSync) { |
| syncLock(); |
| } else { |
| monitorLock(); |
| } |
| } |
| private void syncLock() { |
| lock1.lock(); |
| try { |
| try { |
| barrier.await(); |
| } catch (InterruptedException e) { |
| e.printStackTrace(); |
| System.exit(1); |
| } catch (BrokenBarrierException e) { |
| e.printStackTrace(); |
| System.exit(1); |
| } |
| goSyncDeadlock(); |
| } finally { |
| lock1.unlock(); |
| } |
| } |
| private void goSyncDeadlock() { |
| try { |
| barrier.await(); |
| } catch (InterruptedException e) { |
| e.printStackTrace(); |
| System.exit(1); |
| } catch (BrokenBarrierException e) { |
| e.printStackTrace(); |
| System.exit(1); |
| } |
| lock2.lock(); |
| throw new RuntimeException("should not reach here."); |
| } |
| private void monitorLock() { |
| synchronized (mon1) { |
| try { |
| barrier.await(); |
| } catch (InterruptedException e) { |
| e.printStackTrace(); |
| System.exit(1); |
| } catch (BrokenBarrierException e) { |
| e.printStackTrace(); |
| System.exit(1); |
| } |
| goMonitorDeadlock(); |
| } |
| } |
| private void goMonitorDeadlock() { |
| try { |
| barrier.await(); |
| } catch (InterruptedException e) { |
| e.printStackTrace(); |
| System.exit(1); |
| } catch (BrokenBarrierException e) { |
| e.printStackTrace(); |
| System.exit(1); |
| } |
| synchronized (mon2) { |
| throw new RuntimeException(getName() + " should not reach here."); |
| } |
| } |
| } |
| |
| class Monitor { |
| String name; |
| Monitor(String name) { |
| this.name = name; |
| } |
| } |
| |
| private static void waitForEnterPressed() { |
| try { |
| boolean done = false; |
| while (!done) { |
| char ch = (char) System.in.read(); |
| if (ch<0||ch=='\n') { |
| done = true; |
| } |
| } |
| } |
| catch (IOException e) { |
| e.printStackTrace(); |
| System.exit(0); |
| } |
| } |
| } |