public class DeamThread {
    static class Hello{
        static {
            System.out.println(Thread.currentThread().getName() + " init");
        }
    }
    public static void main(String[] args) {
        ExecutorService threadPool = Executors.newFixedThreadPool(20);
        int i = 0;
        while(i++<20){
            threadPool.execute(new Runnable() {
                @Override
                public void run() {
                    System.out.println(Thread.currentThread().getName() + " start");
                    Hello h = new Hello();
                    System.out.println(Thread.currentThread().getName() + " end");
                }
            });
        }
    }
}