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I was also looking for this information. GC stands for garbage-collector, which collects unused objects during runtime of your app.
Please note that all of this information is based on a post from |
Another place where the Dalvik garbage collector messages are explained is in this video:Google I/O 2011: Memory management for Android Apps
At about 14 minutes into the presentation, he breaks down the message format. (BTW, that video has really good info on debugging memory leaks)
Roughly speaking, the format is [Reason] [Amount Freed], [Heap Statistics], [External Memory Statistics], [Pause Time]
Reason
Viktor/Robert already explained GC_CONCURRENT, GC_FOR_MALLOC,GC_EXTERNAL_ALLOC.
There is also:
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GC_HPROF_DUMP_HEAP- If you dump heap by clicking the "dump heap" button from DDMS or programatically -
GC_EXPLICIT- If you call System.gc()
Amount Freed
E.g. freed 2125K
Self explanatory
Heap Statistics
E.g. 47% free 6214K/11719K
These numbers reflect conditions after the GC ran. The "47% free" and 6214K reflect the current heap usage. The 11719K represents the total heap size. From what I can tell, the heap can grow/shrink, so you will not necessarily have an OutOfMemoryError if
you hit this limit.
External Memory Statistics
E.g external 7142K/8400K
Note: This might only exist in pre-Honeycomb versions of Android (pre 3.0).
Before Honeycomb, bitmaps are allocated external to your VM (e.g. Bitmap.createBitmap() allocates the bitmap externally and only allocates a few dozen bytes on your local heap). Other examples of external allocations are for java.nio.ByteBuffers.
Pause Time
If it's a concurrent GC event, there will be two times listed. One is for a pause before the GC, one is for a pause when the GC is mostly done.E.g.paused 3ms+5ms
For non-concurrent GC events, there is only one pause time and it's typically much bigger.E.g.paused 87ms