Suspiciously short list of threads when recording ANRError as Crashlytics non-fatal exception

[AntonPetrov83]

Hi!

I integrated ANR-WatchDog to a Unity game using custom implementation of UnityPlayerActivity.

At first I released a game with the default behaviour of the ANR-WatchDog.
My app crashed due to unhandled ANRError and Firebase Crashlytics recorded something around 40 threads at this moment including UnityMain thread and others. I used setReportMainThreadOnly() because Crashlytics collects all threads by itself on fatal errors.

Then I turned this crash to a non-fatal using this code:

    @Override protected void onCreate(Bundle savedInstanceState)
    {
        ANRWatchDog watchDog = new ANRWatchDog();
        watchDog.setANRListener(new ANRWatchDog.ANRListener() {
            @Override
            public void onAppNotResponding(ANRError error) {
                FirebaseCrashlytics crashlytics = FirebaseCrashlytics.getInstance();
                crashlytics.recordException(error);
            }
        });
        watchDog.start();

        super.onCreate(savedInstanceState);
    }

This code records ANRError as a non-fatal exception and Crashlytics attaches stack traces contained in ANRError. That is why you do not see setReportMainThreadOnly() here any more. But now crash reports a very short, containing only 8-10 threads. What is strange there were no UnityMain thread while this non-fatal was triggered in the middle of a gameplay.

Please help, any ideas on how to get full list of stack traces attached?

[AntonPetrov83]

Okay, this is by design :(

Under the hood Crashlytics trims stack-traces longer then 1024 entries. ANRError collects all thread stacks as a single long stack-trace and it gets trimmed by Crashlytics.

So the solution is either crash with Fatal error to allow Crashlytics collect all threads or collect threads by ourselves and send it somewhere.

[mastef]

@AntonPetrov83 unrelated but would be cool if you could share your solution on how to use ANR-WatchDog with unity. Lots of people have now ANR issues since recently

[AntonPetrov83]

@AntonPetrov83 unrelated but would be cool if you could share your solution on how to use ANR-WatchDog with unity. Lots of people have now ANR issues since recently

@mastef create a derived class from UnityPlayerActivity like described here: Extending the UnityPlayerActivity Java Code

Then write something like that:

    @Override protected void onCreate(Bundle savedInstanceState)
    {
        ANRWatchDog watchDog = new ANRWatchDog();
        watchDog.setReportMainThreadOnly();
        watchDog.start();

        super.onCreate(savedInstanceState);
    }

[mastef]

@AntonPetrov83 unrelated but would be cool if you could share your solution on how to use ANR-WatchDog with unity. Lots of people have now ANR issues since recently

@mastef create a derived class from UnityPlayerActivity like described here: Extending the UnityPlayerActivity Java Code

Then write something like that:

    @Override protected void onCreate(Bundle savedInstanceState)
    {
        ANRWatchDog watchDog = new ANRWatchDog();
        watchDog.setReportMainThreadOnly();
        watchDog.start();

        super.onCreate(savedInstanceState);
    }

Got there after writing the comment. But the setReportMainThreadOnly is interesting! Thank you for the hint!

[mastef]

@AntonPetrov83 Thanks for the help! For future reference I'm adding the code here. Unfortunately I'm not able to trigger ANRs from Unity.

package com.mycompany.gamepackage;

import com.github.anrwatchdog.ANRError;
import com.github.anrwatchdog.ANRWatchDog;
import com.github.anrwatchdog.ANRWatchDog.ANRListener;
import com.unity3d.player.UnityPlayerActivity;

import android.os.Bundle;
import android.util.Log;

public class GameActivity extends UnityPlayerActivity
{

    // Setup activity layout
    @Override protected void onCreate(Bundle savedInstanceState)
    {
        Log.d("GameActivity", "WatchDog starting");
        new ANRWatchDog(3000)
            .setIgnoreDebugger(true)
            .setReportMainThreadOnly()
            .setANRListener(new ANRWatchDog.ANRListener() {
                @Override
                public void onAppNotResponding(ANRError error) {
                    Log.e("GameActivity", "", error);
                    Log.d("GameActivity", "ANR Caught");
                }
            })
            .start();

        Log.d("GameActivity", "WatchDog started");
        super.onCreate(savedInstanceState);
    }
}

This is confirmed working.

Inside the Unity game loop I tried delaying stuff with System.Threading.Thread.Sleep(6000); but to no avail. Nothing gets triggered. Maybe blocking the Unity game loop does not cause ANRs?

[AntonPetrov83]

Inside the Unity game loop I tried delaying stuff with System.Threading.Thread.Sleep(6000); but to no avail. Nothing gets triggered. Maybe blocking the Unity game loop does not cause ANRs?

Yeah, ANR triggers only when main thread is blocked and Unity runs on Unity-Main thread which is not main ))
To emulate an ANR you can use code:

public class AndroidShowStopper : MonoBehaviour
{
    private static bool _stop;

    public static void Stop()
    {
        _stop = true;
    }
    
#if UNITY_ANDROID
    void Update()
    {
        if (_stop)
        {
            AndroidJavaClass unityPlayer = new AndroidJavaClass("com.unity3d.player.UnityPlayer");
            AndroidJavaObject activity = unityPlayer.GetStatic<AndroidJavaObject>("currentActivity");
            activity.Call("runOnUiThread", new AndroidJavaRunnable(runOnUiThread));
            
            _stop= false;
        }
    }

    void runOnUiThread()
    {
        Debug.Log("I'm running on the Java UI thread!");

        while (true);
    }
#endif
}

Just call AndroidShowStopper.Stop(); somewhere.

[WaheedRashad]

Hi!

I integrated ANR-WatchDog to a Unity game using custom implementation of UnityPlayerActivity.

At first I released a game with the default behaviour of the ANR-WatchDog. My app crashed due to unhandled ANRError and Firebase Crashlytics recorded something around 40 threads at this moment including UnityMain thread and others. I used setReportMainThreadOnly() because Crashlytics collects all threads by itself on fatal errors.

Then I turned this crash to a non-fatal using this code:

    @Override protected void onCreate(Bundle savedInstanceState)
    {
        ANRWatchDog watchDog = new ANRWatchDog();
        watchDog.setANRListener(new ANRWatchDog.ANRListener() {
            @Override
            public void onAppNotResponding(ANRError error) {
                FirebaseCrashlytics crashlytics = FirebaseCrashlytics.getInstance();
                crashlytics.recordException(error);
            }
        });
        watchDog.start();

        super.onCreate(savedInstanceState);
    }

This code records ANRError as a non-fatal exception and Crashlytics attaches stack traces contained in ANRError. That is why you do not see setReportMainThreadOnly() here any more. But now crash reports a very short, containing only 8-10 threads. What is strange there were no UnityMain thread while this non-fatal was triggered in the middle of a gameplay.

Please help, any ideas on how to get full list of stack traces attached?

How to integrate ANR-WatchDog to a Unity game using custom implementation of UnityPlayerActivity?