TextClock memory leak

[namgk]

https://developer.android.com/reference/android/widget/TextClock

LeakTrace information

5446 bytes retained by leaking objects
Signature: 24ae8ab7f39ddd58d1df561358903f7b13726
┬───
│ GC Root: Global variable in native code
│
├─ android.database.ContentObserver$Transport instance
│    Leaking: UNKNOWN
│    Retaining 60 B in 3 objects
│    ↓ ContentObserver$Transport.mContentObserver
│                                ~~~~~~~~~~~~~~~~
├─ android.widget.TextClock$FormatChangeObserver instance
│    Leaking: UNKNOWN
│    Retaining 32 B in 2 objects
│    ↓ TextClock$FormatChangeObserver.this$0
│                                     ~~~~~~
├─ android.widget.TextClock instance
│    Leaking: UNKNOWN
│    Retaining 1.9 kB in 23 objects
│    View not part of a window view hierarchy
│    View.mAttachInfo is null (view detached)
│    View.mID = R.id.time
│    View.mWindowAttachCount = 6
│    mContext instance of dagger.hilt.android.internal.managers.ViewComponentManager$FragmentContextWrapper, wrapping
│    activity omitted.ui.MainActivity with mDestroyed = false
│    ↓ View.mParent
│           ~~~~~~~
├─ android.widget.LinearLayout instance
│    Leaking: UNKNOWN
│    Retaining 6.6 kB in 158 objects
│    View not part of a window view hierarchy
│    View.mAttachInfo is null (view detached)
│    View.mWindowAttachCount = 6
│    mContext instance of dagger.hilt.android.internal.managers.ViewComponentManager$FragmentContextWrapper, wrapping
│    activity omitted.ui.MainActivity with mDestroyed = false
│    ↓ View.mParent
│           ~~~~~~~
╰→ android.widget.FrameLayout instance
​     Leaking: YES (ObjectWatcher was watching this because omitted.ui.ads.AdFragmentClock received
​     Fragment#onDestroyView() callback (references to its views should be cleared to prevent leaks))
​     Retaining 5.4 kB in 142 objects
​     key = f66af549-a226-4bac-af84-61059cefc47b
​     watchDurationMillis = 13975
​     retainedDurationMillis = 8969
​     View not part of a window view hierarchy
​     View.mAttachInfo is null (view detached)
​     View.mWindowAttachCount = 6
​     mContext instance of dagger.hilt.android.internal.managers.ViewComponentManager$FragmentContextWrapper, wrapping
​     activity omitted.ui.MainActivity with mDestroyed = false

Metadata

METADATA
    
    Please include this in bug reports and Stack Overflow questions.
    
    Build.VERSION.SDK_INT: 25
    Build.MANUFACTURER: rockchip
    LeakCanary version: 2.7
    App process name: omitteed
    Stats: LruCache[maxSize=3000,hits=3255,misses=61980,hitRate=4%]
    RandomAccess[bytes=2978775,reads=61980,travel=28206469105,range=13379141,size=20842769]
    Heap dump reason: 6 retained objects, app is visible
    Analysis duration: 14796 ms
    Heap dump file path: /storage/emulated/0/Download/leakcanary-omitted/2021-07-12_20-20-48_751.hprof
    Heap dump timestamp: 1626146466029
    Heap dump duration: 2089 ms
    ====================================

[pyricau]

Sounds like a bug in either the Android SDK or a manufacturer impl, you should file an issue with a repro case, which means you need to figure out how to repro first.

Sources for TextClock are here: https://cs.android.com/android/platform/superproject/+/master:frameworks/base/core/java/android/widget/TextClock.java

Also @romainguy wrote TextClock, I'm sure he'll love being pinged 🤪

[pyricau]

The trace indicates that ContentObserver$Transport.mContentObserver isn't null, and it is set to null when ContentObserver$Transport#releaseContentObserver() is called, so that wasn't called, which means ContentResolver.unregisterContentObserver() wasn't called which means TextClock.unregisterObserver() wasn't called.

However we can see it being called in TextClock.onDetachFromWindow():

    @Override
    protected void onDetachedFromWindow() {
        super.onDetachedFromWindow();

        if (mRegistered) {
            unregisterReceiver();
            unregisterObserver();

            mRegistered = false;
        }
    }

The only way I can see this happening is if TextClock.setShowCurrentUserTime(boolean showCurrentUserTime) is called, as it's the only place adding non symmetric called, and not checking / updating the mRegistered state. Looks like it's only used in KeyguardClockSwitch and SplitClockView.

To investigate further we'd need a heap dump.

[pyricau]

No heap dump, no repro case and no issue filed to Google. Closing.

[JensSchmitt]

I have the same issue! How can I pass a heapdump to you?

[pyricau]

You can upload directly to google issues, or you can uploading to google drive then share the link here and make sure it's shared with my email (py.ricau gmail.com)