Java本机内存使用情况

Question

有没有工具可以知道我的java应用程序使用了多少本机内存？我从我的应用程序中经历过outofmemory:当前设置是:-Xmx900m

电脑,Windows 2003 Server 32位,RAM 4GB.

在Windows上将boot.ini更改为/ 3GB也会有什么不同？如果设置为Xmx900m,可以为此进程分配多少最大本机内存？是1100米吗？

Answer 1

(在我的情况下,我使用java 8)

添加到命令行: -XX:NativeMemoryTracking=summary

然后发射 jcmd <PID> VM.native_memory

你应该得到这样的东西:

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) 

有关更多信息,请参阅https://docs.oracle.com/javase/8/docs/technotes/guides/troubleshoot/tooldescr007.html