Develop Reference

Ensure UI Thread isn't interrupted

I have a GridView full of somewhat complicated views, that are computed based on results downloaded on the fly from the internet in an AsyncTask. While the view is being downloaded, it shows a default:
imageView.setImageDrawable(new ColorDrawable(Color.TRANSPARENT));
When the AsyncTask finishes it gets a Bitmap that was computed for it. I am using an ExecutorService to enable AsyncTask parallelization:
if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.HONEYCOMB) {
loaderPool = Executors.newFixedThreadPool(backendManager.getBackendApplicationContext()
.getResources()
.getInteger(R.integer.loader_thread_count));
}
(I've currently set R.integer.loader_thread_count to 10)
And I start those AsyncTask's as:
if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.HONEYCOMB) {
newTask.executeOnExecutor(loaderPool);
} else {
newTask.execute(); // Pre-Honeycomb Post-Donut is parallelized by default.
}
I make sure to set the thread priority in the AsyncTask so that it doesn't try to compete with anything else:
#Override
protected Object doInBackground(Object... params) {
if (isCancelled()) {
return null;
}
// just in case
android.os.Process.setThreadPriority(android.os.Process.THREAD_PRIORITY_BACKGROUND);
...
But, the ui feels jerky when scrolling the GridView. The issue seems to be that the main thread is getting pre-empted too often:
I would like a large number of threads for when there is high network latency, so that they can all be blocking on network io when necessary. However, I only want those threads to run when the ui has essentially nothing else to do; I'm fine showing transparent views for a while while everything loads, so long as the ui is responsive while it is loading (there are some text views and stuff too so it's not just a blank screen).
How can I instruct android to give greater priority to my ui thread, and/or less priority to my AsyncTasks?

I would like a better answer, but for now this seemed to help a bunch.
While the docs claim for the higher thread priorities that "Applications can not normally change to
this priority", as of a few years ago that was a lie, and seems (?) to apparently still be a lie - https://groups.google.com/forum/#!topic/android-developers/b2SKprSxPvw
As such rather than make the background threads more backgrounded, I made the ui thread more foregrounded in Activity.onCreate(). In case they disallow this sort of thing in the future, I wrap it with a try/catch:
try {
android.os.Process.setThreadPriority(android.os.Process.THREAD_PRIORITY_DISPLAY);
} catch (Throwable t) {}

Android dynamic UI update from AsynchTask/Handler and Thread priorities

I am using an AsynchTask to host a simulator that runs indefinelly and posts the results after each simulation step.
Limiting the simulation loop in background at a maximum of 25Hz, and only calling a javascript function with the results, it works "fine".
Apart from updating a webgl model in a browser, what looks fast enough, I have two more things to update from the Android UI: the FPS indicator and the panel with TextViews representing some of the values. If we forget about the FPS:
The onProgressUpdate() function is already limited to be called at 25Hz, to refresh the model. Now I use another time variable to limit, inside this method, the call to another method that updates the UI panel textViews. It is limited to 1Hz, less than what I actually wanted but fast enough for the kind of information. The method is as clean as possible, all the views are previously loaded to a variable that I keep to not load them every time.
What is the effect: looks like updating 5 textViews takes like one second where all the UI freezes, the touch moves are very very laggy...
I decreased the priority of the background task with:
#Override
protected Boolean doInBackground(ModelSimulation... params) {
Thread.currentThread().setPriority(Thread.MIN_PRIORITY);
...
And used Thread.yield() at the end of the doInBackground method. This improves the behavior to what I explained, without these commands, the behavior is even worst.
My questions are:
-Can I reduce even more the priority if instead of using a background task I use a handler and my own Thread?
-Will a service improve the behavior of the UI?
-Why updating 5 textViews takes so long compared with calling a javascript function that finally will have to use the gpu to change the webgl model?
-Is Android not prepared in any sens to do dynamic applications? How applications like the ones to test sensors update so fast the UI? because there are not standar components like the textViews? (like browser going faster than a textView)
Note: even reducing the refreshing limitations, it produce a laggy effect every time the HUD is updated. In fact I talk about 5 textViews but only updating the FPS indicator produces the same pause. Looks like the only fact of having to switch to the UI thread already consumes this time.
Edit 1:
#Override
protected Boolean doInBackground(ModelSimulation... params) {
Thread.currentThread().setPriority(Thread.MIN_PRIORITY);
if(simulator.getSimulatorStatus().equals(SimulatorStatus.Connected)){
try {
while (true){
//TODO Propagate
long dur = (System.nanoTime()-time_tmp_data);
if(dur<Parameters.Simulator.min_hud_model_refreshing_interval_ns){
try {
long sleep_dur = (Parameters.Simulator.min_hud_model_refreshing_interval_ns-(System.nanoTime()-time_tmp_data))/1000000;
if(sleep_dur>0){
Thread.sleep(sleep_dur);
}
} catch (InterruptedException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
time_tmp_data = System.nanoTime();
SpacecraftState sstate = propagate();
int progress = (int)((extrapDate.durationFrom(finalDate)/mission.sim_duration)*100);
if(sstate!=null){
SimResults results = new SimResults(sstate, progress);
simulator.getSimulationResults().updateSimulation(results.spacecraftState, results.sim_progress);
publishProgress();
}
if(isCancelled())
break;
Thread.yield();
}
} catch (OrekitException e) {
// TODO Auto-generated catch block
e.printStackTrace();
simulator.showMessage(simulator.getContext().getString(R.string.sim_orekit_prop_error)+": "+e.getMessage());
}
}
return true;
}
#Override
protected void onProgressUpdate(Void... values) {
//Update model by push
simulator.getSimulationResults().pushSimulationModel();
//Update GUI HUD
if(time_tmp_gui==0 || (System.nanoTime()-time_tmp_gui)>Parameters.Simulator.min_hud_panel_refreshing_interval_ns){
time_tmp_gui = System.nanoTime();
simulator.getSimulationResults().updateHUD();
}
}
If I comment the line simulator.getSimulationResults().updateHUD(); or directly the contents of the method, it works "fine". And this method is only changing some textviews text:
public synchronized void updateHUD(){
//Log.d("Sim",System.currentTimeMillis()+": "+"pre update gui 1");
activity.runOnUiThread( new Runnable() {
#SuppressLint("ResourceAsColor")
public void run() {
if(view != null){
if(panel_time != null)
panel_time.setText(info.time.replace("T", " "));
if(panel_progress != null)
panel_progress.setProgress(info.progress);
if(panel_vel != null){
panel_vel.setText("Vel. "+String.format("%.2f", info.velocity)+" Km/s");
if(info.velocity>config.limit_velocity)
panel_vel.setTextColor(activity.getResources().getColor(R.color.panel_limit));
else
panel_vel.setTextColor(activity.getResources().getColor(R.color.panel_value));
}
if(panel_accel != null){
panel_accel.setText("Accel. "+String.format("%.2f", info.acceleration)+" Km/s2");
if(info.acceleration>config.limit_acceleration)
panel_accel.setTextColor(activity.getResources().getColor(R.color.panel_limit));
else
panel_accel.setTextColor(activity.getResources().getColor(R.color.panel_value));
}
if(panel_radium != null)
panel_radium.setText("Orbit radium: "+String.format("%.1f", info.orbit_radium)+" Km");
if(panel_mass != null)
panel_mass.setText("Mass: "+String.format("%.1f", info.mass)+" Kg");
if(panel_roll != null)
panel_roll.setText("Rol: "+String.format("%.1f", (180*info.roll/Math.PI))+"º");
if(panel_pitch != null)
panel_pitch.setText("Pitch: "+String.format("%.1f", (180*info.pitch/Math.PI))+"º");
if(panel_yaw != null)
panel_yaw.setText("Yaw: "+String.format("%.1f", (180*info.yaw/Math.PI))+"º");
}
}
});
//Log.d("Sim",System.currentTimeMillis()+": "+"post update gui 1");
}
Edit 2: I can actually remove the runOnUiThread since it is already at that thread, but the effect is the same, this is not the problem.
Edit 3: I tried to comment all the lines of the method updateHUD() and leave only these two:
if(panel_time != null)
panel_time.setText(info.time.replace("T", " "));
The effect is almost the same, if I touch any textView, the animation goes by steps like periodically freezing
Edit 4:
I noticed that the process inside the AsyncTask was taking longer than the available step time so it was never sleeping. I established a safe guard time of 10ms that is slept even if the simulation step is longer than the available time. So, I have minimum 10ms free of each 100ms. The efect stills the same. I am updating at 25Hz the browser and 1Hz a single textview text. If I disable the textview update, the webgl model animates smoothly. On the other hand, if I enable the textview update too, every time the text is updated, there are some miliseconds where the browser animation and its response to touches are blocked. This effect gets worst if I increase the task priority. I tried setting a huge guard of 500ms but the freezing effect stills appearing. I am using XWalkView, can it be something blocking the interaction of this view when UI Thread is acting?
I can't understand why a 4 core 2 RAMgb device needs way more time to compute the same simulation than in Linux or windows desktop PC. I have 25Hz-->40ms of available time and the steps take almost 70ms. In a PC I could keep the simulation at 25Hz in real time. Is there so much shit running in background in Android compared to other OS?

There must be another issue with your code. Try posting your AsyncTask in here.
You could also try something very basic like:
Create a new Thread that loops every 25Hz and update your UI by using the post() method of your UI elements or the runInUiThread() of your Activity. See if there's any code still running inside the UI Thread, that could do heavy work, that can be done outside the UI Thread.

I tried literally everything except for the most logic thing, trying the application without the debugger connected.
The reason to have slower simulation than in a PC, to freese UI events... all because the debugger takes a lot of resources from the device. So, I guess that from this point and avobe I will have to test the application without debugger, what forces me to reboot the phone each time to avoid the "waiting for debugger to connect".
Thank to all who tried.

I could be wrong, but I think that yours problem in synchronization on simulator.getSimulationResults() object. I can't see the realization of the simulator class and realization of the object returned by getSimulationResults(), but I suppose that getSimulationResults() returns the same object every time? If so, then it can be looks like this:
In the AsyncTaks call simulator.getSimulationResults().updateSimulation(...). If this method is synchronized, then this call will be lock the SimulationResults object for AsyncTaks thread.
updateSimulation(...) returns, and publishProgress() is called, but publishProgress() is only schedule the onProgressUpdate(Void... values) in the UI thread.
The new iteration in the AsyncTaks thread can be started befor the UI thread gets the control and executes onProgressUpdate(Void... values). So, AsyncTaks thread goes to the first step.
The UI thread gets the control and executes the onProgressUpdate(Void... values) and synchronized void updateHUD() methods, but updateHUD() can't be executed, because SimulationResults object is locked by the AsyncTaks thread in the updateSimulation(...) method. So the UI thread returns the control to the OS. This may occur many times.
So, onProgressUpdate(Void... values) method and all events in the UI thread can be executed only if the UI thread gets the control in the right moment when updateSimulation(...) method is not called in the AsyncTask thread.
You can check this idea by replacing the public synchronized void update HUD() on the public void update HUD(), and write something randomly in the TextView.
In any case, the use of AsyncTask in this case is not the best idea. AsyncTask's are executed in the TheadPool, but in the Android system this pool can consist from only one thread. So, all AsyncTask's will be executed one by one in the one thread.

How can I keep UI elements responsive while my program is working?

The UI I am creating includes a button, which once pressed, is supposed to find and display values repetitively until the user presses the button again.
This is my button's initialization with the listener:
pollOn = false;
pollButton = (Button) findViewById( R.id.pollButton );
pollButton.setOnClickListener( new OnClickListener() {
public void onClick(View v) {
// TODO Auto-generated method stub
Log.i( "POLL BUTTON", "onClick" );
if( !pollOn ) {
Log.i( "POLL BUTTON", "!pollOn" );
pollOn = true;
methodToReadAndDisplayData();
} else {
Log.i( "POLL BUTTON", "else pollOn" );
pollOn = false;
}
}
});
It is not shown here to make things easier to read, but the way I currently have it working is to call the methodToReadAndDisplayData() 5 times in a for loop and then stop.
So when I press the pollButton initially, the UI freezes and Log.i("POLL BUTTON", "onClick") is displayed at the top of LogCat. I then press the pollButton while it appears to be frozen, and after all of the work is done and the UI unfreezes, Log.i("POLL BUTTON", "onClick") is shown at the very end of my LogCat. The way I am interpretting this is that the button click is entered into a queue, and the onClick method is called after all 5 iterations of the for loop have been completed.
Another large part of this problem is that the work being done is mainly in a native library, and is called using the NDK. I am unsure if this has anything to do with the UI freezing, but it definitely increases the processing time needed.
If anything is unclear or confusing please let me know and I will try to clarify things.
Any information on this situation would be greatly appreciated.

Doing some stuff while keeping the UI responsive can achieved by many methods, two of them are very common. Async Task and threads.
AsyncTask:
It's a class which have a few methods which help you to do time consuming work while updating the UI at the same time. For Example: If you want to search a specific word in a big document, do the reading and searching stuff in doInBackground() (a method of AsyncTask class) and you can display a progress bar and notify the user with your progress with onProgressUpdate(). This gives your app more professional feel and at the same time helps you executing time consuming task in background.
Threads:
They are simple runnable threads. You can execute non UI stuff with these threads but you can't perform UI tasks in them (as UI is not thread safe). For dealing with UI in these threads, you will have to use Handlers, which is quite cumbersome for beginners to get a grip and understanding of them.
So depending on your needs and app you can choose the one best suits you.

Because you're running on the main thread the system UI freezes, you'd be better off running in a new thread which would leave your UI running as normal. Below is an example of how to run your method in a new thread.
new Thread(new Runnable() {
#Override
public void run() {
methodToReadAndDisplayData();
}
}).start();
Note that if your method interacts with the UI in any way, you need to do it via the following:
When you want to update your UI:
Handler threadHandler = new Handler();
threadHandler.post(updateRunnable);
Update your UI here:
Runnable updateRunnable = new Runnable() {
public void run() {
example.setText(newValue);
}
};
Try that and see if there's any improvement. I've not worked with the NDK, just the standard SDK so there may be difference I'm unaware of.

Do it on another thread. Use an AsyncTask to call methodToReadAndDisplayData.

keeping track of the progress of file downloads in AsyncTask

I asked a similar question here AsyncTask and Progressbar.
What I am doing is I am scheduling the download of more than two files one by one in the background AsyncTask.. UI thread may need one of those files at any point of time depending upon the user interaction.. And if the file download is not complete when the UI thread asks for it, I need to show the progress of download of that particular file..
I have seen quiet a few answers about showing the progress bar of a particular file download. But my requirement is somewhat different. I need to keep track of the progress of the file downloads occurring in the background.

As you're using an AsyncTask you have the option to use onProgressUpdate(Progress...), invoked on the UI thread after a call to publishProgress(Progress...).
E.g.
private class DownloadFilesTask extends AsyncTask<File, Integer, Long> {
protected Long doInBackground(File... file) {
// This will call onProgressUpdate
publishProgress((int) ((i / (float) count) * 100));
}
// this will be called on the UI thread
protected void onProgressUpdate(Integer... progress) {
setProgressPercent(progress[0]);
}
protected void onPostExecute(Long result) {
showDialog("Downloaded " + result + " bytes");
}
}
If you're not using an AsyncTask you can create a Handler and post messages to the UI thread that way.
But as you mention file downloads some things to consider (from Android docs):-
The device might not have enough space for the expansion files, so you should check before beginning the download and warn the user if there's not enough space.
File downloads should occur in a background service in order to avoid blocking the user interaction and allow the user to leave your app while the download completes.
A variety of errors might occur during the request and download that you must gracefully handle.
Network connectivity can change during the download, so you should handle such changes and if interrupted, resume the download when possible.
While the download occurs in the background, you should provide a notification that indicates the download progress, notifies the user when it's done, and takes the user back to your application when selected.
Luckily all of the above are covered in a library from Google, which provides a download with notifications of progress (even if you quit your app). You can use it, or modify the source to your own needs. More info here
http://developer.android.com/google/play/expansion-files.html#AboutLibraries

Each download should be run on its own thread (in case one file is smaller, one server faster etc).
Try extending thread or creating a runnable that is parameterized by the URI or other identifier for the download. Once you have that, you can invoke 2 threads that'll run until complete. If you need to update the UI (progress bar), you will need to implement a handler and send a message from a thread to the handler. e.g.
in the main activity class:
public static final int UPDATE_PROGRESS_BAR =0;
public final Handler uiHander = new Handler(){
public void handleMessage(Message msg){
switch(msg.what){
case UPDATE_PROGRESS_BAR: // Something like this to handle the case of progress bar update
int updateAmount = msg.obj;
// do something to update prog. bar
break;
and then in the thread just send that message, it'll need a reference to the handler
uiHander.obtainMessage(<activity name>.UPDATE_PROGRESS_BAR,<integer update>).sendToTarget();
This may be the most portable way of doing it as async tasks implementation has changed version to version and may or may not execute both downloads in parallel (which you clearly want)

You can use DownloadManager but it won't show progress in your Views. Other option is use an ExecutorService and submit custom Runnable tasks. Wrap ExecutorService in a custom class that maintains a map of tasks submitted. Whenever a file is needed you can query this class whether a task is completed or not, and also show a ListView of running tasks.

Measure Android app startup time

What is the most precise way to measure startup time of an Android app?
By startup time I mean the difference between 2. and 3. :
The app process is not running
User clicks on app icon in the launcher
Main Activity is fully initialized
So I basically need to somehow get time elapsed since JVM started and log it.

I understand I am too late to answer, nonetheless, this precisely answers the question.
This information gets logged on Logcat by default for API version 19 or higher.
From Android 4.4 (API level 19), logcat includes an output line containing a value called Displayed. This value represents the amount of time elapsed between launching the process and finishing drawing the corresponding activity on the screen.
ActivityManager: Displayed com.android.myexample/.StartupTiming: +3s534ms
The key is looking for it in the right place -
If you’re tracking logcat output from the command line, or in a terminal, finding the elapsed time is straightforward. To find elapsed time in Android Studio, you must disable filters in your logcat view. Disabling the filters is necessary because the system server, not the app itself, serves this log.
The extracts are from the documentation.

I'm going to interpret your question as 'Is my app startup time fast enough. How can I check I have done everything I can do?'
The startup time is largely a false metric as it will vary across devices and ROMs. I guess what you're most likely to be interested in is how much of your code is taking a long time to execute and what is potentially blocking the main thread.
I've found the most effective way of doing this is to use Traceview on the app start and then reviewing how long it takes the method to execute and if there are any gaps on the main thread.
Start tracing:
public class MyApplication extends Application {
#Override
public void onCreate() {
super.onCreate();
Debug.startMethodTracing("startup");
}
}
Stop tracing:
#Override
public void onViewCreated(final View view, final Bundle savedInstanceState) {
super.onViewCreated(view, savedInstanceState);
Debug.stopMethodTracing();
}
Once the trace has been collected, you should be able to see anything that is having a major impact on startup time. In my case, seen below, there was a big gap on the UI thread where is was being blocked.
It transpired that both Crashlytics and Coremetrics were requiring a call to randomUUID() which was then being synchronized across threads and blocking the main thread. The solution was just to spin up a new thread to initialise the Coremetrics code.
This is something I would not have otherwise picked up with just measuring the startup time, but it actually sped up the app 'startup time' by a few hundred milliseconds.
Here's another snapshot after spinning off a separate thread for Coremetrics initialisation:

Check in adb shell in below manner.
adb shell
adb logcat -b events | grep am_activity_launch_time
[Output]
01-01 12:32:53.469 1236 1262 I am_activity_launch_time:
[0,205360373,com.sec.android.app.clockpackage/.ClockPackage,378,**378**,0]
Remarks:
Launch time for Clock is 378ms.

Wrap the entire onCreate() method in a TimingLogger. Just put this at the beginning:
TimingLogger timings = new TimingLogger(TAG, "methodA");
and this at the end:
timings.dumpToLog();
If you want to drop times at some intermediate step, you can do timings.addSplit("name"); to get the time it took to get to that step.

A simple way to display startup time in android.
Sometimes the Displayed line in the logcat output contains an additional field for total time. For example:
ActivityManager: Displayed com.android.myexample/.StartupTiming: +3s534ms (total +1m22s643ms)
In this case, the first time measurement is only for the activity that was first drawn
Source: Time to initial display

It is possible to implement time tracking using the next code:
Override your Application:
public class CustomApplication extends Application {
public final static long APP_START_TIME = System.currentTimeMillis();
/**
* Do all other application stuff
*/
}
And add few rows to your main Activity:
public class MainActivity extends AppCompatActivity {
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
final View contentView = findViewById(android.R.id.content);
contentView.getViewTreeObserver().addOnGlobalLayoutListener(new ViewTreeObserver.OnGlobalLayoutListener() {
#Override
public void onGlobalLayout() {
if (Build.VERSION.SDK_INT >= 16) {
contentView.getViewTreeObserver().removeOnGlobalLayoutListener(this);
} else {
contentView.getViewTreeObserver().removeGlobalOnLayoutListener(this);
}
long launchTime = System.currentTimeMillis() - CustomApplication.APP_START_TIME;
Log.e("TEST", "App launch time = " + launchTime);
}
});
}
}
And don't forget to define your custom application in Manifest:
<application
android:label="#string/app_name"
android:name=".CustomApplication" >
</application>
Important: You have to kill your application before launch, because Application stores static variable which tracks initial time.

Use SysTrace
Also the Trace class can be used to measure sections using
Trace.beginSection("name");
Trace.endSection();
This YouTube video is a quick primer as well.

I think this has been built into Firebase Console, under performance now

One possibility would be is to save the time at the beginning of the onCreate() method and at the end of the onCreate() method and then subtract those times from each other to get the time taken to initialize the app.