android主线程忙的时候是不会去执行messagequeue上的message的

代码如下：

public static long zero;

    void test(){
        zero = System.currentTimeMillis();
        Thread thread = new Thread(){
            @Override
            public void run() {
                super.run();
                Log.e(TAG, "subthread before sleep" + (System.currentTimeMillis() - zero));
                try {
                    Thread.sleep(1000);
                } catch (InterruptedException e) {
                    e.printStackTrace();
                }
                Log.e(TAG, "subthread after sleep" + (System.currentTimeMillis() - zero));
                handler.sendMessage(Message.obtain());
                Log.e(TAG, "subthread after sendMessage" + (System.currentTimeMillis() - zero));

            }
        };
        thread.start();
        Log.e(TAG, "mainthread before sleep" + (System.currentTimeMillis() - zero));
        try {
            Thread.sleep(2500);
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
        Log.e(TAG, "mainthread after sleep" + (System.currentTimeMillis() - zero));

    }

    MyHandler handler = new MyHandler(this);
    private static class MyHandler extends Handler {

        private WeakReference activityWeakReference;

        public MyHandler(MainActivity activity) {
            activityWeakReference = new WeakReference<>(activity);
        }

        @Override
        public void handleMessage(Message msg) {
            super.handleMessage(msg);
            MainActivity activity = activityWeakReference.get();
            if (activity != null) {
                //处理handler消息，本次用不到
                Log.e(TAG, "main handler handleMessage" + (System.currentTimeMillis() - zero));

            }
        }
    }

放在oncreate中执行 打印如下

MainActivity: mainthread before sleep1
MainActivity: subthread before sleep1
MainActivity: subthread after sleep1003
MainActivity: subthread after sendMessage1004
MainActivity: mainthread after sleep2504
MainActivity: main handler handleMessage2582

要么就是主线程也通过messagequeue来运行，要么就是观察主线程idle状态