jmap查看jvm的heap区内存情况

通过jmap可以查看到启动jvm时,java heap区的各个分配及使用情况:

[root@emos-webdb bin]# ./jmap -heap 25109    

 Attaching to process ID 25109, please wait...
Debugger attached successfully.
Server compiler detected.
JVM version is 24.79-b02

using thread-local object allocation.
Parallel GC with 23 thread(s)

Heap Configuration:
   MinHeapFreeRatio = 0
   MaxHeapFreeRatio = 100
   MaxHeapSize      = 16917725184 (16134.0MB)
   NewSize          = 1310720 (1.25MB)
   MaxNewSize       = 17592186044415 MB
   OldSize          = 5439488 (5.1875MB)
   NewRatio         = 2
   SurvivorRatio    = 8
   PermSize         = 21757952 (20.75MB)
   MaxPermSize      = 85983232 (82.0MB)
   G1HeapRegionSize = 0 (0.0MB)


Heap Usage:
PS Young Generation
Eden Space:
   capacity = 1845493760 (1760.0MB)
   used     = 598348504 (570.6296005249023MB)
   free     = 1247145256 (1189.3703994750977MB)
   32.42213639346036% used
From Space:
   capacity = 84934656 (81.0MB)
   used     = 1409024 (1.34375MB)
   free     = 83525632 (79.65625MB)
   1.6589506172839505% used
To Space:
   capacity = 85983232 (82.0MB)
   used     = 0 (0.0MB)
   free     = 85983232 (82.0MB)
   0.0% used
PS Old Generation
   capacity = 254279680 (242.5MB)
   used     = 194559112 (185.54602813720703MB)
   free     = 59720568 (56.95397186279297MB)
   76.51382603596166% used
PS Perm Generation
   capacity = 68157440 (65.0MB)
   used     = 68071656 (64.9181900024414MB)
   free     = 85784 (0.08180999755859375MB)
   99.87413846529446% used


24558 interned Strings occupying 2745240 bytes.