查看运行中的java程序的堆大小

实现思路:
    使用jmap加上heap参数即可查看
例:
    jmap -heap 进程号

 
[root@****01 ~]# jmap -heap 24095
Attaching to process ID 24095, please wait...
Debugger attached successfully.
Server compiler detected.
JVM version is 25.211-b12

using thread-local object allocation.
Parallel GC with 8 thread(s)

Heap Configuration:
   MinHeapFreeRatio         = 0
   MaxHeapFreeRatio         = 100
   MaxHeapSize              = 2147483648 (2048.0MB)    ---堆最大容量
   NewSize                  = 131072000 (125.0MB)
   MaxNewSize               = 715653120 (682.5MB)
   OldSize                  = 263192576 (251.0MB)
   NewRatio                 = 2
   SurvivorRatio            = 8
   MetaspaceSize            = 134217728 (128.0MB)
   CompressedClassSpaceSize = 528482304 (504.0MB)
   MaxMetaspaceSize         = 536870912 (512.0MB)
   G1HeapRegionSize         = 0 (0.0MB)

Heap Usage:
PS Young Generation
Eden Space:
   capacity = 287834112 (274.5MB)
   used     = 34339368 (32.748573303222656MB)
   free     = 253494744 (241.75142669677734MB)
   11.93026349844177% used
From Space:
   capacity = 1048576 (1.0MB)
   used     = 1015808 (0.96875MB)
   free     = 32768 (0.03125MB)
   96.875% used
To Space:
   capacity = 5242880 (5.0MB)
   used     = 0 (0.0MB)
   free     = 5242880 (5.0MB)
   0.0% used
PS Old Generation
   capacity = 166723584 (159.0MB)
   used     = 158310968 (150.97710418701172MB)
   free     = 8412616 (8.022895812988281MB)
   94.95415357673693% used

30169 interned Strings occupying 2716760 bytes.