JAVA的异步线程与同步线程问题.

Question

 public static void main(String[] args) {        int threadCount = 1000; // 线程数量(1000)        CountDownLatch countDownLatch = new CountDownLatch(threadCount);        List<Object> list = new ArrayList<Object>();                MyThreadTest myThreadTest = new MyThreadTest(list);               MySync mySync = MySync.getMySync(myThreadTest,countDownLatch);        // mySync = new MySync(myThreadTest,countDownLatch);  // 为什么放开这段代码,会连 System.out.println("========:"+list.size()); 都不会执行了?                try {        for(int i =0;i<threadCount;i++){            mySync.run();        }            countDownLatch.await(); // 主线程等待所有子线程执行完成，再向下执行        } catch (InterruptedException e) {            e.printStackTrace();        }        System.out.println("========:"+list.size());    }}class MyThreadTest implements Runnable{    private List<Object> list;        private int i = 0;        public MyThreadTest(List<Object> list){        this.list = list;    }        @Override    public void run() {        i++;        list.add(new Object());        System.out.println(i);    }}class MySync{    private static CountDownLatch countDownLatch;    private static Runnable runn;        public MySync(){}        @SuppressWarnings("static-access")       public MySync(Runnable runn,CountDownLatch countDownLatch){        Enhancer enhancer = new Enhancer();        enhancer.setSuperclass(MySync.class);        enhancer.setCallback(new MethodInterceptorImpl());        MySync mySync = (MySync)enhancer.create();        mySync.countDownLatch = countDownLatch;        mySync.runn = runn;    }        @SuppressWarnings("static-access")    public static MySync getMySync(Runnable runn,CountDownLatch countDownLatch){         Enhancer enhancer = new Enhancer();         System.out.println("========:"+list.size()); 使用计数来进行了同步,这段代码不应该是最后才会输出的吗?测试结果是不确定什么时候输出.如果放开注释的那段代码,为什么连System.out.println("========:"+list.size()); 都不输出了?这是什么原因造成的?(不知道这段代码还有什么BUG,请各位大神指导)