Android - Forcing ANR for testing purpose

Question

Why i can't force Android ANR with this code? No log messages or pop up. The application is just launched lazily.

[UPDATE]

I can't get it even sleeping a View.setOnClickListener or BroadcastReceiver.onReceive!

Is there a trick?

public class MainActivity extends Activity {

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        try {
            Thread.sleep(10000);
        } catch (InterruptedException e) {
            Log.e("Test", "", e);
        }
    }
}

I'm using Samsung GT-6200L with stock Android 3.2

Maybe onCreate is not on the UI thread yet, try adding sleep on onStart or onResume — Marcio Covre, Oct 23 '12 at 16:21
There is an option for developers in Android 4.0 - "show all ANRs" or something like this. Maybe you have such an option on Android 3.2? It is turned off by default, so common users don't get disturbed. — olshevski, Oct 23 '12 at 16:31
Very weird... I can't get it even sleeping a View.setOnClickListener or BroadcastReceiver.onReceive... — CelinHC, Oct 23 '12 at 16:40
@Kzinch I saw that in ICS/JellyBeans in Setting > Developer Options. Unfortunatelly there isn't this option in 3.2, at least in Samsung GT-6200... — CelinHC, Oct 23 '12 at 16:47

NikkyD · Answer 1 · 2012-10-24T08:42:23.530

13

Try it in onTouchEvent. In onCreate your activity is not fully running

@Override
public boolean onTouchEvent(MotionEvent event) {
    Log.d(TAG,"onTouchEvent");  
    while(true) {}
}

edited Oct 24 '12 at 08:42

answered Oct 23 '12 at 16:58

NikkyD

2,209
1
16
31

this has to work. Thread.sleep is always executed and unless interrupted (which you could check via logcat message) it will hold the program and android WILL throw ANR if the program is not responding to any callback within 3 seconds. – NikkyD Oct 24 '12 at 08:37
@CelinHC When nothing else happens on the main thread, you will not see an ANR pop up immediately. You have to wait for it or you can trigger it by pressing the back button and wait a few seconds. – Albert-Jan Verhees May 15 '18 at 09:11
@Albert-JanVerhees This can be the answer I was expecting for long time. I will test it. – CelinHC May 15 '18 at 16:12
because Android gives the app a lot of time to do work if there is nothing it has to respond to (until a threshold is met), but if a response to something is required and the app does not respond an ANR is thrown – NikkyD May 15 '18 at 16:24

score 5 · Answer 2 · answered Aug 09 '17 at 09:55

The ANR-WatchDog project has a test app that produces ANRs in a reliable manner (as reliable as ANRs can be): the app hangs because of a deadlock.

The gist of it:

Prepare a lock object as a private field in your activity: final Object mutex = new Object();

Have a thread that performs some work in a critical section, and an android.os.Handler that posts work depending on the same lock.

new Thread(new Runnable() {
  @Override
  public void run() {
    synchronized (mutex) {
      while (true) {
        try {
           Thread.sleep(60000);
        }
        catch (InterruptedException e) {
          e.printStackTrace();
        }
      }
    }
  }
}).start();

new Handler().postDelayed(new Runnable() {
  @Override
  public void run() {
    synchronized (mutex) {
      // Shouldn't happen
      throw new IllegalStateException();
    }
  }
}, 1000);

Putting the above code snippet inside a button click handler, for example, should do the trick.

score 3 · Answer 3 · answered Oct 23 '12 at 16:23

3

Try using:

public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
    int a=0;
    while(true) {
        a++;
    }       
}

Your code probably didn't work because it got setup too early, and the Activity probably wasn't fully initialized and created yet. With the above code, launch the activity and touch/swipe on the screen and wait for the ANR dialog to popup.

answered Oct 23 '12 at 16:23

Raghav Sood

81,899
22
187
195

Really? I tried it out on my device, and it works like a charm. – Raghav Sood Oct 23 '12 at 17:33

score 3 · Answer 4 · answered Jun 14 '13 at 10:48

3

I've been facing the same issue yesterday, and I've found out that using a plain debug build ANR dialogs simply won't show up. (Although the UI thread was completely hanged.)

But after exporting and properly signing the application the dialogs were popped up properly (in every cases mentioned above). However I am still not sure what really prevents to pop up ANR messages, maybe someone else can clarify this later...

answered Jun 14 '13 at 10:48

peter42

31
1

they will show up if you turn this function on in Developers options in the device Settings – alla Jan 27 '20 at 14:36

score 1 · Answer 5 · answered Oct 23 '12 at 16:59

1

Make a button in your activity.

public void onBtn1(View v) {
   int a = 0;
   while(true) {
      a++;
   }
}

Make the button execute the above code. Spam click the button with your finger =)

answered Oct 23 '12 at 16:59

hiBrianLee

1,847
16
19

score 0 · Answer 6 · answered Jan 10 '14 at 08:02

I used this code for force ANR

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
    }

    public void force(View view){
        while(true) {}
    }

I just created a simple button in the xml file and set android:onClick=force

Android - Forcing ANR for testing purpose

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