StackOverflow2013

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copied!<p>Another place where the Dalvik garbage collector messages are explained is in this video: <a href="http://www.youtube.com/watch?v=_CruQY55HOk">Google I/O 2011: Memory management for Android Apps</a></p> <p>At about 14 minutes into the presentation, he breaks down the message format. (BTW, that video has really good info on debugging memory leaks)</p> <p>Roughly speaking, the format is <code>[Reason] [Amount Freed], [Heap Statistics], [External Memory Statistics], [Pause Time]</code></p> <h2>Reason</h2> <p>Viktor/Robert already explained <code>GC_CONCURRENT</code>, <code>GC_FOR_MALLOC</code>, <code>GC_EXTERNAL_ALLOC</code>.</p> <p>There is also:</p> <ul> <li><p><code>GC_HPROF_DUMP_HEAP</code> - If you dump heap by clicking the "dump heap" button from DDMS or programatically</p></li> <li><p><code>GC_EXPLICIT</code> - If you call System.gc()</p></li> </ul> <h2>Amount Freed</h2> <p>E.g. <code>freed 2125K</code></p> <p>Self explanatory</p> <h2>Heap Statistics</h2> <p>E.g. <code>47% free 6214K/11719K</code></p> <p>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.</p> <h2>External Memory Statistics</h2> <p>E.g <code>external 7142K/8400K</code></p> <p>Note: This might only exist in pre-Honeycomb versions of Android (pre 3.0).</p> <p>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.</p> <h2>Pause Time</h2> <p>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. <code>paused 3ms+5ms</code></p> <p>For non-concurrent GC events, there is only one pause time and it's typically much bigger. E.g. <code>paused 87ms</code></p>

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