I would like to know exactly where the JVM is spending the memory, almost bit by bit! how to do so?

I already mentioned jcmd on my previous reply. But now, I will show this feature to actually take an compare baselines:

$ jcmd 26283 VM.native_memory 26283: Native Memory Tracking: Total: reserved=3075884KB, committed=1815600KB - Java Heap (reserved=1335296KB, committed=1335296KB) (mmap: reserved=1335296KB, committed=1335296KB) - Class (reserved=1149983KB, committed=118375KB) (classes #20513) (malloc=3103KB #30610) (mmap: reserved=1146880KB, committed=115272KB) - Native Memory Tracking (reserved=5453KB, committed=5453KB) <--- Native memory (malloc=255KB #3577) (tracking overhead=5198KB)

Generating diff:

$ jcmd 26283 VM.native_memory detail.diff 
26283: 
Native Memory Tracking: Total: 
reserved=2984385KB +296KB, committed=1725525KB +296KB - 
Java Heap (reserved=1335296KB, committed=1335296KB) (mmap: reserved=1335296KB, committed=1335296KB) - 
Native Memory Tracking (reserved=5572KB +79KB, committed=5572KB +79KB) <--- this means that +79Kb were added 
(malloc=348KB +63KB #4926 +890) (tracking overhead=5224KB +16KB)

This means that 79Kb were added tot eh native tracking and using a simple baseline one can see even how much the GC increased/decreased the usage.

GC (reserved=135778KB, committed=66846KB)
(malloc=24654KB #37248)
(mmap: reserved=111124KB, committed=42192KB +79KB)

Compiler (reserved=1142KB, committed=1142KB +79KB)
(malloc=1033KB #1307)
(arena=110KB #5)