jvm：查看jvm各塊兒空間的使用詳細情況，如堆，方法區

查詢一個項目的使用堆棧情況，ps  - ef | grep 項目名

拿到端口，然後使用如下命令，查詢項目使用堆棧詳細信息

[root@xg ~]# jmap -heap 15653
Attaching to process ID 15653, please wait...
Debugger attached successfully.
Server compiler detected.
JVM version is 25.181-b13

using thread-local object allocation.
Parallel GC with 18 thread(s)

Heap Configuration:
   MinHeapFreeRatio         = 0
   MaxHeapFreeRatio         = 100
   MaxHeapSize              = 1879048192 (1792.0MB)
   NewSize                  = 625999872 (597.0MB)
   MaxNewSize               = 625999872 (597.0MB)
   OldSize                  = 1253048320 (1195.0MB)
   NewRatio                 = 2
   SurvivorRatio            = 8
   MetaspaceSize            = 134217728 (128.0MB)
   CompressedClassSpaceSize = 260046848 (248.0MB)
   MaxMetaspaceSize         = 268435456 (256.0MB)
   G1HeapRegionSize         = 0 (0.0MB)

Heap Usage:
PS Young Generation
Eden Space:
   capacity = 500170752 (477.0MB)
   used     = 261428000 (249.31716918945312MB)
   free     = 238742752 (227.68283081054688MB)
   52.26775035418304% used
From Space:
   capacity = 62914560 (60.0MB)
   used     = 46544976 (44.38874816894531MB)
   free     = 16369584 (15.611251831054688MB)
   73.98124694824219% used
To Space:
   capacity = 62914560 (60.0MB)
   used     = 0 (0.0MB)
   free     = 62914560 (60.0MB)
   0.0% used
PS Old Generation
   capacity = 1253048320 (1195.0MB)
   used     = 148909216 (142.01089477539062MB)
   free     = 1104139104 (1052.9891052246094MB)
   11.883756884969927% used

45427 interned Strings occupying 4989312 bytes.
[root@xg ~]#