线程池

是先开启corePoolSize大小的线程数，如果在来了线程就放入等待队列里，如果队列方满了，就再开启线程最大不能大于maximumPoolSize。
当前时刻最大调用量等于 maximumPoolSize+BlockingQueue.size

 // 创建数组型缓冲等待队列
        BlockingQueue<Runnable> bq = new ArrayBlockingQueue<Runnable>(7);
        ExecutorService  service = new ThreadPoolExecutor(2,4,100,TimeUnit.MILLISECONDS,bq);
        Runnable runnable = new Runnable() {
            @Override
            public void run() {
                try {
                    TimeUnit.SECONDS.sleep(1);
                } catch (InterruptedException e) {
                    e.printStackTrace();
                }
                System.out.println(Thread.currentThread().getName());
                try {
                    TimeUnit.SECONDS.sleep(1);
                } catch (InterruptedException e) {
                    e.printStackTrace();
                }
            }
        };
        Thread  t1 = new Thread(runnable,"线程1");
        Thread  t2 = new Thread(runnable,"线程2");
        Thread  t3 = new Thread(runnable,"线程3");
        Thread  t4= new Thread(runnable,"线程4");
        Thread  t5 = new Thread(runnable,"线程5");
        Thread  t6 = new Thread(runnable,"线程6");

        Thread  t7 = new Thread(runnable,"线程7");
        Thread  t8 = new Thread(runnable,"线程8");
        Thread  t9 = new Thread(runnable,"线程9");
        service.execute(t1);
        service.execute(t2);
        service.execute(t3);
        service.execute(t4);
        service.execute(t5);
        service.execute(t6);
        service.execute(t7);
        service.execute(t8);
        service.execute(t9);
        TimeUnit.SECONDS.sleep(10);