public ThreadPoolExecutor(int corePoolSize,
                          int maximumPoolSize,
                          long keepAliveTime,
                          TimeUnit unit,
                          BlockingQueue<Runnable> workQueue,
                          ThreadFactory threadFactory,
                          RejectedExecutionHandler handler)

 /**
     * Creates a new {@code ThreadPoolExecutor} with the given initial
     * parameters.
     *
     * @param corePoolSize the number of threads to keep in the pool, even
     *        if they are idle, unless {@code allowCoreThreadTimeOut} is set
     * @param maximumPoolSize the maximum number of threads to allow in the
     *        pool
     * @param keepAliveTime when the number of threads is greater than
     *        the core, this is the maximum time that excess idle threads
     *        will wait for new tasks before terminating.
     * @param unit the time unit for the {@code keepAliveTime} argument
     * @param workQueue the queue to use for holding tasks before they are
     *        executed.  This queue will hold only the {@code Runnable}
     *        tasks submitted by the {@code execute} method.
     * @param threadFactory the factory to use when the executor
     *        creates a new thread
     * @param handler the handler to use when execution is blocked
     *        because the thread bounds and queue capacities are reached
     * @throws IllegalArgumentException if one of the following holds:<br>
     *         {@code corePoolSize < 0}<br>
     *         {@code keepAliveTime < 0}<br>
     *         {@code maximumPoolSize <= 0}<br>
     *         {@code maximumPoolSize < corePoolSize}
     * @throws NullPointerException if {@code workQueue}
     *         or {@code threadFactory} or {@code handler} is null
     */
    public ThreadPoolExecutor(int corePoolSize,
                              int maximumPoolSize,
                              long keepAliveTime,
                              TimeUnit unit,
                              BlockingQueue<Runnable> workQueue,
                              ThreadFactory threadFactory,
                              RejectedExecutionHandler handler)

public static ExecutorService newFixedThreadPool(int nThreads) {
        return new ThreadPoolExecutor(nThreads, nThreads,
                                      0L, TimeUnit.MILLISECONDS,
                                      new LinkedBlockingQueue<Runnable>());
    }

public static ExecutorService newCachedThreadPool() {
    return new ThreadPoolExecutor(0, Integer.MAX_VALUE,
                                    60L, TimeUnit.SECONDS,
                                    new SynchronousQueue<Runnable>());
 }

 // 线程池默认使用的是abortPolicy, 现在将任务持有的Q大小设置为1,说明等待的任务最有只能有一个
// ,如果等待任务超过一个则会触发abortPolicy,abortPolicy会抛出异常
ExecutorService executorService =
        new ThreadPoolExecutor(1, 1, 0L, TimeUnit.MILLISECONDS, new LinkedBlockingQueue<>(1));
executorService.submit(()-> {
    SleepUtil.sleepSeconds(10);
    System.out.println("task 1");
});
executorService.submit(()-> {
    System.out.println("task 2");
});
executorService.submit(()-> {
    System.out.println("task 3");
});

public void rejectedExecution(Runnable r, ThreadPoolExecutor e) {
    if (!e.isShutdown()) {
        r.run();
    }
}

public class BoundedExecutor {
  private final Executor executor;
  private final Semaphore semaphore;

  public BoundedExecutor(Executor executor, Semaphore semaphore) {
    this.executor = executor;
    this.semaphore = semaphore;
  }

  public void submitTask(final Runnable command) throws InterruptedException {
    // 提交任务之前,先获取semaphore,当semaphore数量为0时,方法阻塞,等待任务执行结束释放,这样可以保证提交任务的数量
    semaphore.acquire();
    try {
      executor.execute(
        () -> {
          try {
            command.run();
          } finally {
            semaphore.release();
          }
        }
      );
    } catch (RejectedExecutionException e) {
      semaphore.release();
    }
  }
}

public class TimingThreadPool extends ThreadPoolExecutor {
  private final ThreadLocal<Long> startTime = new ThreadLocal<>();
  private final Logger logger = Logger.getLogger("TimingThreadPool");
  private final AtomicLong numTasks = new AtomicLong();
  private final AtomicLong totalTime = new AtomicLong();

  @Override
  protected void beforeExecute(Thread t, Runnable r) {
    super.beforeExecute(t, r);
    logger.fine(String.format("Thread %s: start %s", t, r));
    startTime.set(System.nanoTime());
  }

  @Override
  protected void afterExecute(Runnable r, Throwable t) {
    try {
      long end = System.nanoTime();
      long taskTime = end - startTime.get();

      // 记录任务的执行数量
      numTasks.incrementAndGet();

      // 记录任务的执行时间
      totalTime.addAndGet(taskTime);
      logger.fine(
        String.format("Thread %s: end %s, time=%dns", t, r, taskTime)
      );
    } finally {
      super.afterExecute(r, t);
    }
  }

  @Override
  protected void terminated() {
    try {
      // 打印每个任务执行的平均时间
      logger.info(
        String.format(
          "Terminated: avg time=%dns",
          totalTime.get() / numTasks.get()
        )
      );
    } finally {
      super.terminated();
    }
  }
}

public interface ThreadFactory {
  Thread newThread(Runnable r);
}