public class MyAppThread extends Thread {    public static final String DEFAULT_NAME = "MyAppThread";    private static volatile boolean debugLifecycle = false;    private static final AtomicInteger created = new AtomicInteger();    private static final AtomicInteger alive = new AtomicInteger();    private static final Logger log = Logger.getAnonymousLogger();    public MyAppThread(Runnable r) {        this(r, DEFAULT_NAME);
    }    public MyAppThread(Runnable runnable, String name) {        super(runnable, name + "-" + created.incrementAndGet());        //设置该线程工厂创建的线程的 未捕获异常的行为
        setUncaughtExceptionHandler(new Thread.UncaughtExceptionHandler() {            public void uncaughtException(Thread t,
                                          Throwable e) {
                log.log(Level.SEVERE,                        "UNCAUGHT in thread " + t.getName(), e);
            }
        });
    }    public void run() {        // Copy debug flag to ensure consistent value throughout.
        boolean debug = debugLifecycle;        if (debug) log.log(Level.FINE, "Created " + getName());        try {
            alive.incrementAndGet();            super.run();
        } finally {
            alive.decrementAndGet();            if (debug) log.log(Level.FINE, "Exiting " + getName());
        }
    }    public static int getThreadsCreated() {        return created.get();
    }    public static int getThreadsAlive() {        return alive.get();
    }    public static boolean getDebug() {        return debugLifecycle;
    }    public static void setDebug(boolean b) {
        debugLifecycle = b;
    }
}

//串行化
    void processSequentially(List elements) {        for (Element e : elements)
            process(e);
    }    //并行化
    void processInParallel(Executor exec, List elements) {        for (final Element e : elements)
            exec.execute(new Runnable() {                public void run() {
                    process(e);
                }
            });
    }

//串行 计算compute 和串行迭代
    public  void sequentialRecursive(List> nodes, Collection results) {        for (Node n : nodes) {
            results.add(n.compute());
            sequentialRecursive(n.getChildren(), results);
        }
    }    //并行 计算compute 和串行迭代
    public  void parallelRecursive(final Executor exec, List> nodes, final Collection results) {        for (final Node n : nodes) {
            exec.execute(() -> results.add(n.compute()));
            parallelRecursive(exec, n.getChildren(), results);
        }
    }    //调用并行方法的操作
    public  Collection getParallelResults(List> nodes)            throws InterruptedException {
        ExecutorService exec = Executors.newCachedThreadPool();
        Queue resultQueue = new ConcurrentLinkedQueue();
        parallelRecursive(exec, nodes, resultQueue);
        exec.shutdown();
        exec.awaitTermination(Long.MAX_VALUE, TimeUnit.SECONDS);        return resultQueue;
    }

public class ConcurrentPuzzleSolver  {    private final Puzzle puzzle;    private final ExecutorService exec;    private final ConcurrentMap seen;    protected final ValueLatch> solution = new ValueLatch>();    public ConcurrentPuzzleSolver(Puzzle puzzle) {        this.puzzle = puzzle;        this.exec = initThreadPool();        this.seen = new ConcurrentHashMap();        if (exec instanceof ThreadPoolExecutor) {
            ThreadPoolExecutor tpe = (ThreadPoolExecutor) exec;
            tpe.setRejectedExecutionHandler(new ThreadPoolExecutor.DiscardPolicy());
        }
    }    private ExecutorService initThreadPool() {        return Executors.newCachedThreadPool();
    }    public List solve() throws InterruptedException {        try {
            P p = puzzle.initialPosition();
            exec.execute(newTask(p, null, null));            // 等待ValueLatch中闭锁解开，则表示已经找到答案
            PuzzleNode solnPuzzleNode = solution.getValue();            return (solnPuzzleNode == null) ? null : solnPuzzleNode.asMoveList();
        } finally {
            exec.shutdown();//最终主线程关闭线程池        }
    }    protected Runnable newTask(P p, M m, PuzzleNode n) {        return new SolverTask(p, m, n);
    }    protected class SolverTask extends PuzzleNode implements Runnable {
        SolverTask(P pos, M move, PuzzleNode prev) {            super(pos, move, prev);
        }        public void run() {            //如果有一个线程找到了答案，则return，通过ValueLatch中isSet CountDownlatch闭锁实现；            //为类避免死锁，将已经扫描的节点放入set集合中，避免继续扫描产生死循环
            if (solution.isSet() || seen.putIfAbsent(pos, true) != null){                return; // already solved or seen this position            }            if (puzzle.isGoal(pos)) {
                solution.setValue(this);
            } else {                for (M m : puzzle.legalMoves(pos))
                    exec.execute(newTask(puzzle.move(pos, m), m, this));
            }
        }
    }
}