Java native memory usage

Question

Is there any tool to know how many native memory has been used from my java application ? I've experienced outofmemory from my application : Current setting is : -Xmx900m

Computer, Windows 2003 Server 32bit, RAM 4GB.

Also is changing boot.ini to /3GB on windows, will make any difference? If is set Xmx900m, how much max native memory can be allocated for this process ? is it 1100m ?

Answer 1

This article gives some good information about hunting down native memory issues and explains how you run out of native memory.

Answer 2

(in my case I use java 8)

add to command line: -XX:NativeMemoryTracking=summary

then launch jcmd <PID> VM.native_memory

You should get something like this:

Total: reserved=3863657KB, committed=1679977KB
-                 Java Heap (reserved=1843200KB, committed=824320KB)
                            (mmap: reserved=1843200KB, committed=824320KB) 

-                     Class (reserved=1311974KB, committed=298726KB)
                            (classes #52579)
                            (malloc=5350KB #76340) 
                            (mmap: reserved=1306624KB, committed=293376KB) 

-                    Thread (reserved=263278KB, committed=263278KB)
                            (thread #256)
                            (stack: reserved=262140KB, committed=262140KB)
                            (malloc=839KB #1280) 
                            (arena=299KB #510)

-                      Code (reserved=278521KB, committed=164773KB)
                            (malloc=28921KB #37983) 
                            (mmap: reserved=249600KB, committed=135852KB) 

-                        GC (reserved=114897KB, committed=77093KB)
                            (malloc=13729KB #67925) 
                            (mmap: reserved=101168KB, committed=63364KB) 

-                  Compiler (reserved=461KB, committed=461KB)
                            (malloc=330KB #1138) 
                            (arena=131KB #3)

-                  Internal (reserved=13877KB, committed=13877KB)
                            (malloc=13845KB #72978) 
                            (mmap: reserved=32KB, committed=32KB) 

-                    Symbol (reserved=28871KB, committed=28871KB)
                            (malloc=24740KB #275452) 
                            (arena=4131KB #1)

-    Native Memory Tracking (reserved=8393KB, committed=8393KB)
                            (malloc=45KB #523) 
                            (tracking overhead=8348KB)

-               Arena Chunk (reserved=184KB, committed=184KB)
                            (malloc=184KB) 

For more information see https://docs.oracle.com/javase/8/docs/technotes/guides/troubleshoot/tooldescr007.html