Java通过Semaphore控制同一时间只有3个线程运行

怎么控制同一时间只有3个线程运行？
直接上代码

import java.util.Date;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.Semaphore;

public class SemaphoreThreadPoolExample {

    private static final int THREAD_COUNT = 10;
    private static final int MAX_CONCURRENT_THREADS = 3;

    public static void main(String[] args) {
    	// 创建了一个固定大小为10的线程池
        ExecutorService executor = Executors.newFixedThreadPool(THREAD_COUNT);
        // 初始化一个信号量 semaphore，设置最大并发线程数为3
        Semaphore semaphore = new Semaphore(MAX_CONCURRENT_THREADS);

		// 创建10个线程任务
        for (int i = 0; i < THREAD_COUNT; i++) {
            Runnable task = new Task(semaphore);
            executor.execute(task);
        }

        executor.shutdown();
    }

    static class Task implements Runnable {
        private final Semaphore semaphore;

        public Task(Semaphore semaphore) {
            this.semaphore = semaphore;
        }

        @Override
        public void run() {
            try {
                semaphore.acquire(); // 获取许可
                System.out.println(new Date() + "Thread " + Thread.currentThread().getId() + " is running.");
                // 暂停一会
                Thread.sleep(2000);
            } catch (InterruptedException e) {
                e.printStackTrace();
            } finally {
                semaphore.release(); // 释放许可
            }
        }
    }
}