Java GC runs very often after minimal allocations

I'm writing a realtime game for an android, and so I would like to minimize garbage collection / collection as recommended in the androids Design for Performance tutorial.

I have a very simple game that doesn't use a lot of memory (and 2-3% of the heap according to the hprof heap dump), but my parallel gc runs like a clock every 7 seconds, always freeing about 1MB of memory. My game is completely paused and not doing anything interesting, and running allocation tracking for 5 seconds shows very little allocation. This is a complete dump of the allocation tracker after opening for a few seconds, which accounts for less than 1KB of allocations (basically just dalvik stuff and my lock / unlock method).

19  24  byte[]  5   dalvik.system.NativeStart   run 
18  12  java.lang.Integer   5   java.lang.Integer   valueOf 
17  24  org.apache.harmony.dalvik.ddmc.Chunk    5   org.apache.harmony.dalvik.ddmc.DdmServer    dispatch    
16  17  byte[]  5   android.ddm.DdmHandleHeap   handleREAQ  
15  24  org.apache.harmony.dalvik.ddmc.Chunk    5   android.ddm.DdmHandleHeap   handleREAQ  
14  28  java.util.concurrent.locks.AbstractQueuedSynchronizer$Node  10  java.util.concurrent.locks.AbstractQueuedSynchronizer   addWaiter   
13  28  java.util.concurrent.locks.AbstractQueuedSynchronizer$Node  10  java.util.concurrent.locks.AbstractQueuedSynchronizer   addWaiter   
12  28  java.util.concurrent.locks.AbstractQueuedSynchronizer$Node  10  java.util.concurrent.locks.AbstractQueuedSynchronizer   addWaiter   
11  28  java.util.concurrent.locks.AbstractQueuedSynchronizer$Node  10  java.util.concurrent.locks.AbstractQueuedSynchronizer   addWaiter   
10  28  java.util.concurrent.locks.AbstractQueuedSynchronizer$Node  10  java.util.concurrent.locks.AbstractQueuedSynchronizer   addWaiter   
9   28  java.util.concurrent.locks.AbstractQueuedSynchronizer$Node  10  java.util.concurrent.locks.AbstractQueuedSynchronizer   addWaiter   
8   28  java.util.concurrent.locks.AbstractQueuedSynchronizer$Node  10  java.util.concurrent.locks.AbstractQueuedSynchronizer   addWaiter   
7   28  java.util.concurrent.locks.AbstractQueuedSynchronizer$Node  10  java.util.concurrent.locks.AbstractQueuedSynchronizer   addWaiter   
6   28  java.util.concurrent.locks.AbstractQueuedSynchronizer$Node  10  java.util.concurrent.locks.AbstractQueuedSynchronizer   addWaiter   
5   28  java.util.concurrent.locks.AbstractQueuedSynchronizer$Node  10  java.util.concurrent.locks.AbstractQueuedSynchronizer   addWaiter   
4   28  java.util.concurrent.locks.AbstractQueuedSynchronizer$Node  10  java.util.concurrent.locks.AbstractQueuedSynchronizer   addWaiter   
3   24  byte[]  5   dalvik.system.NativeStart   run 
2   12  java.lang.Integer   5   java.lang.Integer   valueOf 
1   24  org.apache.harmony.dalvik.ddmc.Chunk    5   org.apache.harmony.dalvik.ddmc.DdmServer    dispatch    

      

        
        
        
      

    

However, despite all this, I constantly see about 1 MB of collection every few seconds:

03-09 21:41:56.665: D/dalvikvm(4210): GC_CONCURRENT freed 934K, 58% free 3069K/7175K, external 2847K/3550K, paused 3ms+2ms
03-09 21:42:03.685: D/dalvikvm(4210): GC_CONCURRENT freed 937K, 58% free 3069K/7175K, external 2847K/3550K, paused 3ms+1ms
03-09 21:42:10.705: D/dalvikvm(4210): GC_CONCURRENT freed 937K, 58% free 3069K/7175K, external 2847K/3550K, paused 5ms+2ms
03-09 21:42:17.715: D/dalvikvm(4210): GC_CONCURRENT freed 934K, 58% free 3069K/7175K, external 2847K/3550K, paused 3ms+1ms
03-09 21:42:24.725: D/dalvikvm(4210): GC_CONCURRENT freed 934K, 58% free 3069K/7175K, external 2847K/3550K, paused 2ms+3ms

      

        
        
        
      

    

I know I am running out of time, although I would not want 10 milliseconds to be accidentally stolen from one of my frames if I can avoid it. My question is I don't see anything in the allocation tracker, just what can allocate so much memory in just a few seconds? I don't think this is something in the background of the phone, because as soon as I exit the game, I no longer see the GC (or very rarely).

My render thread is using GLSurfaceView which pretty much only works when paused, but I'm just stumped where my memory is going.

Any thoughts are appreciated.