Why is Android 4.0 / Ice Cream Sandwich allocating

Question

I noticed that on my Galaxy Nexus that android.content.res.Resources is allocating about 11MB. I discovered this as I was in the process of profiling things using DDMS and the "Dump HPROF file" option. So, I spent two hours trying to see if the allocation was due to something in my code or supporting libraries. I removed all my data, a ton of classes, all my libraries, and saw no change. After placing a breakpoint in my code at the beginning of the onCreate() method of the activity, it showed that the 11MB allocation is already present.

After being thoroughly confused, I decided to connect my rooted Nook Color running CM7 to see what it was reporting for initial memory usage for the exact same application. The worst case memory "Problem Suspect" reported by the MAT weighs in at a mere 896KB.

Is ICS that top-heavy? Am I missing something here? As far as I can tell, my application is functioning correctly, but having the heap usage indicate 97% full has me worried about potential failures.

If it helps, MAT was indicating that the primary objects consuming all the memory were Bitmaps, BitmapDrawables, and NinePatchDrawables. I don't understand where these allocations are coming from.

Answer 1

Pre-Honeycomb (<3.0), Bitmaps were allocated in native heap and did not appear in Dalvik heap dumps as shown by Eclipse MAT, etc. This native allocation still contributed towards maximum Dalvik heap limits for an application, and still caused garbage collection to run at approximately the correct time when approaching a low memory situation. This usage can be measured with Debug.getNativeHeapAllocatedSize().

Since Android 3.0 (including ICS), it now allocates the pixel data for Bitmaps in normal byte arrays in Dalvik heap. The practical effects of this are better/simplified garbage collection behaviour for Bitmaps (since they can be treated in a more orthodox way) and the ability to track Bitmap allocations in Dalvik heap dumps.

I do not think the actual memory usage for a particular application is significantly different between pre-Honeycomb and more recent releases, and that this is just a matter of an alternative accounting practice.

Memory Analysis for Android

BitMaps in Android