Question

My activity keeps a certain number of references to preview images from the camera in a Map object. This takes a lot of memory. I’m monitoring the memory usage using:

    Runtime runtime = Runtime.getRuntime();
    long allocated = runtime.totalMemory();
    long free = runtime.freeMemory();
    long used = allocated  - free;

When I kill my app (back key), the activity is destroyed. When I start my app again, I can see that the memory was not cleared. The “used” figure starts at the same value and then goes up as new frames arrive.

When I look at the “dominator_tree” after I “Dump HPROF”, I can see two instances of my activity, both taking a lot of memory.

When I override onDestroy() and I clear() the preview frames map object, this doesn’t seem to happen.

I’m probably missing something here but I thought all memory should be deallocated after my activity is destroyed (after the garbage collection process), why do I have to manually clear() the map? Other objects I create don’t seem to require this.

I tried setting android:launchMode=”singleInstance” but this doesn’t seem to have any affect.

Thanks!

Answer 1

in order to understand what’s happening, in the dominator tree, on your activity click with the right button, look for PATH to GC ROOT and select the option that exclude weak/soft/phantom references. That would give you an idea why the system could not destroy your activity (if you are leaking something or what else)