调用AsyncTask的excute方法不能立即执行程序的原因分析及改善方案

LinkedBlockingQueue<Runnable> blockingQueue = new LinkedBlockingQueue<Runnable>();
ExecutorService exec = new ThreadPoolExecutor(1, 1, 0L, TimeUnit.MILLISECONDS, blockingQueue);
new MyFileToBitmap(viewHold.ivPhone, archice.getFilePath()).executeOnExecutor(exec,URl);