memory management - android:largeHeap="true" convention?

Question

I'm writing an image gallery app and I keep running into out of memory errors. I cache all my images but the problem occurs when I try switching between images really fast. I'm assuming the app is allocating memory faster than the GC has time to free them up (because the crash doesn't happen when I switch images slowly).

After banging my head against this problem for days, I finally decided to give largeHeap setting in the manifest file a try. After this setting, my app no longer crashes no matter how fast I switch between images.

Now, I want to know if there is any convention or general guideline to using largeHeap setting because it probably wouldn't make much sense if, say, a note taking app used largeHeap. Generally speaking, what apps are a good candidate for largeHeap setting?

Thanks

Answer 1

Generally speaking, what apps are a good candidate for largeHeap setting?

Ones where you can justify to the user why you're forcing all their other apps out of memory, to give you an outsized amount of heap space.

Personally, I would not consider "an image gallery app" to qualify. AutoCAD, video editors, and the like would qualify.

With respect to your memory management issues, make sure that you are using inBitmap on BitmapOptions when running on API Level 11+, so you recycle existing buffers rather than go through garbage collection. Particularly for an image gallery, where you probably have a lot of fairly consistent thumbnail sizes, recycling existing buffers will be a huge benefit. This can help both overall memory consumption (i.e., you are truly out of memory) and memory fragmentation (i.e., you get an OutOfMemoryError with plenty of heap space, but no single block big enough for your allocation, due to Android's frakkin' non-compacting garbage collector).

You might also consider looking at existing image cache implementations, such as the one that Picasso has, to see if there are some tips you could learn (or possibly just reuse).