new AsyncTask<Void,Void,Void>() {

            private ProgressDialog mProgressDialog;

            @Override
            protected void onPreExecute() {
                Log.i(TAG,"Pre execute: " + System.currentTimeMillis());
                super.onPreExecute();

                mProgressDialog = ProgressDialog.show(NewWeatherActivity.this,null,getResources().getString(R.string.weather_is_updating));
                mProgressDialog.setCancelable(false);

                Log.i(TAG,"Pre executed: " + System.currentTimeMillis());
            }

            @Override
            protected Void doInBackground(Void... voids) {
                Log.i(TAG,"Do in background: " + System.currentTimeMillis());
                // Some actions
                Log.i(TAG,"Done in background: " + System.currentTimeMillis());
                return null;
            }

            @Override
            protected void onPostExecute(Void aVoid) {
                Log.i(TAG,"Post execute: " + System.currentTimeMillis());
                super.onPostExecute(aVoid);

                mProgressDialog.dismiss();
                Log.i(TAG,"Post executed: " + System.currentTimeMillis());
            }
        }.execute();

日志：

I/TVLauncher/NewWeatherActivity(21691): Pre execute: 1354798705667
I/TVLauncher/NewWeatherActivity(21691): Pre executed: 1354798705713
I/TVLauncher/NewWeatherActivity(21691): Do in background:
1354798724063 I/TVLauncher/NewWeatherActivity(21691): Done in
background: 1354798724083 I/TVLauncher/NewWeatherActivity(21691): Post
execute: 1354798724083 I/TVLauncher/NewWeatherActivity(21691): Post
executed: 1354798725046

因此,onPreExecute和doInBackground之间的延迟大约是19秒.为什么？