While running my apps, I have got this kind of logs:
GC_EXTERNAL_ALLOC freed 2K, 38% free 8772K/14087K, external 17480K/17998K, paused 87ms
GC_FOR_MALLOC freed 0K, 38% free 8772K/14087K, external 17480K/17998K, paused 67ms
GC_CONCURRENT freed 2125K, 47% free 6214K/11719K, external 7142K/8400K, paused 3ms+5ms
Does anyone know what these logs mean? Thanks in advance!
Thanks!
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]
Viktor/Robert already explained GC_CONCURRENT
, GC_FOR_MALLOC
, GC_EXTERNAL_ALLOC
.
There is also:
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()
E.g. freed 2125K
Self explanatory
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.
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.
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
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 Robert on a similiar question posted here on stackoverflow. All credit (as long as this is correct) goes to Robert.
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