Changing activity from live data is causing memory leak

Question

My code:

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main_navigation);
    bottomNavigationView = findViewById(R.id.bottom_navigation);
    subscribeObservers();
}

private void subscribeObservers() {
    if (!sessionManager.getAuthedUser().hasActiveObservers()) {
        sessionManager.getAuthedUser().observe(this, new Observer<AuthResource<LoggedUser>>() {
            @Override
            public void onChanged(@Nullable AuthResource<LoggedUser> loggedUserAuthResource) {
                if (loggedUserAuthResource != null) {
                    switch (loggedUserAuthResource.status) {
                        case AUTHENTICATED:
                            Log.d(TAG, "onChanged: Auth success");
                            break;
                        case LOADING:
                            Log.d(TAG, "onChanged: Auth in progress");
                            break;
                        case NOT_AUTHENTICATED:
                            goToWelcomeScreen();
                            Log.d(TAG, "onChanged: Auth failed");
                            break;
                        case ERROR:
                            Log.d(TAG, "onChanged: Auth error");
                            break;
                    }
                }
            }
        });
    }
}

protected void goToWelcomeScreen() {
    Intent intent = new Intent(this, WelcomeActivity.class);
    finish();
    startActivity(intent);
}

This is my session manager method:

    private void initAuthedUser() {
        authedUser.setValue(AuthResource.loading((LoggedUser) null));
        final LiveData<LoggedUser> source = ribonyRepository.getAuthedUser();
        authedUser.setValue(AuthResource.notAuthenticated(null));
    }

    public LiveData<AuthResource<LoggedUser>> getAuthedUser() {
        return authedUser;
    }

As you can see if i run goToWelcomeScreen method in observer my activity is leaking. Here leak logs:

LibraryLeak(className=com.impact.ribony.activities.MainNavigationActivity, leakTrace=
┬
├─ android.app.ActivityThread
│    Leaking: NO (a class is never leaking)
│    GC Root: System class
│    ↓ static ActivityThread.sCurrentActivityThread
│                            ~~~~~~~~~~~~~~~~~~~~~~
├─ android.app.ActivityThread
│    Leaking: UNKNOWN
│    ↓ ActivityThread.mNewActivities
│                     ~~~~~~~~~~~~~~
├─ android.app.ActivityThread$ActivityClientRecord
│    Leaking: UNKNOWN
│    ↓ ActivityThread$ActivityClientRecord.nextIdle
│                                          ~~~~~~~~
├─ android.app.ActivityThread$ActivityClientRecord
│    Leaking: UNKNOWN
│    ↓ ActivityThread$ActivityClientRecord.activity
│                                          ~~~~~~~~
╰→ com.impact.ribony.activities.MainNavigationActivity
​     Leaking: YES (Activity#mDestroyed is true and ObjectWatcher was watching this)
​     key = 4f1783be-bb8f-45df-96bb-e961b3277a1a
​     watchDurationMillis = 5196
​     retainedDurationMillis = 190
, retainedHeapByteSize=1213860, pattern=instance field android.app.ActivityThread$ActivityClientRecord#nextIdle, description=Android AOSP sometimes keeps a reference to a destroyed activity as a nextIdle client record in the android.app.ActivityThread.mActivities map. Not sure what's going on there, input welcome.)

An interesting thing is if i change my onCreate to below then my activity is not leaking. (I removed goToWelcomeScreen call from subscribeObservers method.)

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main_navigation);
    bottomNavigationView = findViewById(R.id.bottom_navigation);
    subscribeObservers();
    goToWelcomeScreen();
}

What can cause to this problem? How can I resolve it?

Thanks

Answer 1

This is identified by LeakCanary as a "library leak", which means it looks like a known leak in the Android Framework. See the description in the trace you pasted:

Android AOSP sometimes keeps a reference to a destroyed activity as a nextIdle client record in the android.app.ActivityThread.mActivities map. Not sure what's going on there, input welcome.

It sounds like you found a way to make the problem go away, which is a great first step. Looks like if you're switching activities during onCreate() you don't have the issue, but the live data is introducing a delay that's causing this to happen.