This is a follow up on TextureGroup#1136. Our experiment results show that clearing data frequently is the cause of our TextureGroup#1 crash. @maicki and I believe that this is because if the collection view is being used, silently clearing its data without notifying the backing UICollectionView can put it out-of-sync and causes mayhem next time the collection view processes a batch update. If you look at the stack trace closely, you'll notice that the crash doesn't occur on the same run loop that clearData is called. This made it extremely tricky to investigate and identify the root cause.

Another interesting question would be whether or not we want to clear the data during deallocation at all, since the data will be cleared out soon anyway.