Will the Guru

If you add -XX:+HeapDumpOnOutOfMemoryError on the JVM argument, when OOM occurs it’ll leave a heap dump.

How to use MAT to analyze heap dump file

1. After opening up the .hprof file, you’ll see below overview
   • 
2. Dominator Tree will show what’s consuming most of the heap spaces
   • 
   • 
   • Shallow Heap: The size of the object itself
   • Retained Heap: The size of the other objects that it is referring
3. Leak Suspects will show suspicious thread and the stacktraces
   • 
   • 
4. Histogram will show list of objects by class. Using histogram, we can get a clue of suspects
   • 

Reference

• https://m.blog.naver.com/2feelus/220780114184