用什么来当做水池中的1000吨水？

package practice2;

import java.util.concurrent.*;
import java.util.concurrent.locks.Condition;
import java.util.concurrent.locks.ReentrantLock;

/**
 * 演示每个任务执行前后放钩子函数
 */
public class PauseableThreadPool1 extends ThreadPoolExecutor {

    public PauseableThreadPool1(int corePoolSize, int maximumPoolSize, long keepAliveTime, TimeUnit unit, BlockingQueue<Runnable> workQueue) {
        super(corePoolSize, maximumPoolSize, keepAliveTime, unit, workQueue);
    }

    public PauseableThreadPool1(int corePoolSize, int maximumPoolSize, long keepAliveTime, TimeUnit unit, BlockingQueue<Runnable> workQueue, ThreadFactory threadFactory) {
        super(corePoolSize, maximumPoolSize, keepAliveTime, unit, workQueue, threadFactory);
    }

    public PauseableThreadPool1(int corePoolSize, int maximumPoolSize, long keepAliveTime, TimeUnit unit, BlockingQueue<Runnable> workQueue, RejectedExecutionHandler handler) {
        super(corePoolSize, maximumPoolSize, keepAliveTime, unit, workQueue, handler);
    }

    public PauseableThreadPool1(int corePoolSize, int maximumPoolSize, long keepAliveTime, TimeUnit unit, BlockingQueue<Runnable> workQueue, ThreadFactory threadFactory, RejectedExecutionHandler handler) {
        super(corePoolSize, maximumPoolSize, keepAliveTime, unit, workQueue, threadFactory, handler);
    }
    //在暂停方法中先把标记位设置一下，为了让布尔值的并发修改是安全的，给它上一把锁
    private final ReentrantLock lock = new ReentrantLock();
    private Condition unpaused = lock.newCondition();
    private boolean isPaused;

    //重写的方法，用来识别下方的标记位
    //每一次执行任务之前，都会调用beforeExecute()方法，并且在这个方法中会去检查while (isPaused)这里是不是被标记为现在想暂停了，如果想暂停就
    @Override
    protected void beforeExecute(Thread t, Runnable r) {
        super.beforeExecute(t, r);
        lock.lock();
        //如果检测到是true了，说明我们想让它暂停了
        try {
            while (isPaused) {
            //暂停之后，就用Condition来让线程进行休眠
                unpaused.await();
            }
        } catch (InterruptedException e) {
            e.printStackTrace();
        }finally {
            lock.unlock();
        }
    }
    //暂停方法
    private void pause() {
        //用这个锁，必须加上try catch finally，否则可能出现这个锁永远无法释放
        lock.lock();
        try {
            isPaused = true;
        }finally {
            lock.unlock();
        }
    }
    //恢复方法，既然已经恢复，就让之前被暂停的那些给唤醒
    public void resume() {
        lock.lock();
        try {
            //然后把标记位设置回去，是false
            isPaused = false;
            //唤醒
            unpaused.signalAll();
        }finally {
            lock.unlock();
        }
    }
    public static void main(String[] args) throws InterruptedException {


        //创建一个可暂停线程池对象
        PauseableThreadPool1 pauseableThreadPool = new PauseableThreadPool1(1, 1, 10l,
                TimeUnit.SECONDS, new LinkedBlockingQueue<>());
        //创建一个线程，打印信息
        Runnable runnable = new Runnable() {
            @Override
            public void run() {
                try {
                    Thread.sleep(10);
                    System.out.println("正在放水");
                } catch (InterruptedException e) {
                    System.out.println("暂停放水中。。。。。。。。。");
                }
            }
        };
        System.out.println("上班啦,水池放入1000吨水");
        //往线程池中添加1000个任务
        for (int i = 0; i < 1000; i++) {
            pauseableThreadPool.execute(runnable);
        }
        System.out.println(pauseableThreadPool.getQueue().size() + "<--------1");
        //当它执行200毫秒之后，调用pause()方法，让它暂停
        //Thread.sleep(200);
        pauseableThreadPool.pause();
        System.out.println("中午啦，回家吃饭啦，水池被暂停了 还剩" + pauseableThreadPool.getQueue().size() + "吨水");
        System.out.println("线程池被暂停了");
        /*//让线程池恢复
        Thread.sleep(200);
        pauseableThreadPool.resume();
        System.out.println("线程池被恢复了");*/
    }

}

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为什么线程休眠200秒，队列的尺寸就会减少。线程不休眠，队列的尺寸就不减少。  线程都休眠了，休眠状态应该不做事情，怎么还会使队列减少？

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