Integer taskCount =700;

// 锁住所有线程，等待并发执行

final CountDownLatch begin =new CountDownLatch(1);

final ExecutorService exec =Executors.newFixedThreadPool(taskCount);

for (int index =0; index < taskCount; index++){

final int NO= index +1;

    Runnable run =new Runnable() {

@Override

        public void run() {

try {

// 等待，所有一起执行

                begin.await();

                //开始模拟等待。。。

                //Thread.sleep((long) (Math.random() * 10000));

            }catch (InterruptedException e){

e.printStackTrace();

            }

finally {

}

}

};

    exec.submit(run);

}

System.out.println("开始执行");

// begin减一，开始并发执行

begin.countDown();

//关闭执行

exec.shutdown();