Android GC行为

Question

I am trying to understand why android GC behaves the way it does,

• VM Heap is set to 512 MB
• Runtime.getRuntime maxMemory is 512 MB
• Runtime.getRuntime totalMemory is 13 MB
• Runtime.getRuntime freeMemory is 3 MB

I am always within +/- 2-3 MB of these values.

My code is functional so I am using a lot objects but I am no where near 512 MB yet I am constantly seeing GC calls in my logcat especially in tight loops. Why doesn't it just let the heap grow? and GC in small increments instead of pausing my app every time for 300 ms.

Is there any way for me to have a little more control over the garbage collection process (this won't be a market app I have no problem with installing a custom rom.) other than stock answer being change your coding style do not create a lot of objects, since I see a similar behavour on a real device (a quad 1,2 ghz machine with 2 gb of ram when no other app is running it is kind of annoying to have a machine this powerfull and not be able to code the way I like.)

Answer 1

The main problem is that an app runs in a VM and each VM has its limit. As long as you are not going native (NDK) you will have to live with the little RAM your VM gets.

I have no problem with installing a custom rom.

If you want to build your own ROM (or search for one with configurable settings), increase the size per VM and be happy with it.

My code is functional so I am using a lot objects

Well there is a difference between "using a lot of objects" and "using a lot of objects with damn short life time". But as you don't wanna hear about it...