Java VisualVM是否提供堆转储的正确堆大小（.hprof文件）

Question

I am analyzing a OutOfMemory issue. I got a dump of 800 MB (.hprof file) when i open it in MAT it shows heap size 53.2 MB as below

Same dump i opened in Java VisualVM and I see Heap size around 769 MB

  Date taken: Tue Mar 18 05:25:59 IST 2014 File: C:\\Users\\ABC\\Desktop\\Memory\\MemoryDump.hprof File size: 789.1 MB Total bytes: 768,683,549 Total classes: 9,288 Total instances: 7,081,010 Classloaders: 2,924 GC roots: 2,496 Number of objects pending for finalization: 0 

I read one article which shows MAT skips unreachable objects so doesnt report exact heap size.

What does Total Bytes of VisulaVM shows here : Heap Size or (Heap + Non Heap size) or anything else?

Answer 1

Total Bytes是堆转储中所有对象的大小的总和。

Answer 2

Eclipse MAT removes the unreachable object and other junk left over by GC in JVM. Read more:

http://wiki.eclipse.org/MemoryAnalyzer/FAQ#Problems_Interpreting_Results