jmap使用

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使用 -heap 查看heap空间概要

jmap -heap 41565 > ~/jmap.txt  

Console Output

Attaching to process ID 41565, please wait...  
Debugger attached successfully.  
Server compiler detected.  
JVM version is 25.131-b11  
  
using parallel threads in the new generation.  
using thread-local object allocation.  
Concurrent Mark-Sweep GC  
  
Heap Configuration:  
   MinHeapFreeRatio         = 40  
   MaxHeapFreeRatio         = 70  
   MaxHeapSize              = 1073741824 (1024.0MB)  
   NewSize                  = 89456640 (85.3125MB)  
   MaxNewSize               = 348913664 (332.75MB)  
   OldSize                  = 178978816 (170.6875MB)  
   NewRatio                 = 2  
   SurvivorRatio            = 8  
   MetaspaceSize            = 21807104 (20.796875MB)  
   CompressedClassSpaceSize = 1073741824 (1024.0MB)  
   MaxMetaspaceSize         = 17592186044415 MB  
   G1HeapRegionSize         = 0 (0.0MB)  
  
Heap Usage:  
New Generation (Eden + 1 Survivor Space):  
   capacity = 314048512 (299.5MB)  
   used     = 314048496 (299.49998474121094MB)  
   free     = 16 (1.52587890625E-5MB)  
   99.99999490524573% used  
Eden Space:  
   capacity = 279183360 (266.25MB)  
   used     = 279183360 (266.25MB)  
   free     = 0 (0.0MB)  
   100.0% used  
From Space:  
   capacity = 34865152 (33.25MB)  
   used     = 34865136 (33.24998474121094MB)  
   free     = 16 (1.52587890625E-5MB)  
   99.99995410890507% used  
To Space:  
   capacity = 34865152 (33.25MB)  
   used     = 0 (0.0MB)  
   free     = 34865152 (33.25MB)  
   0.0% used  
concurrent mark-sweep generation:  
   capacity = 724828160 (691.25MB)  
   used     = 724828160 (691.25MB)  
   free     = 0 (0.0MB)  
   100.0% used  
  
38460 interned Strings occupying 4469136 bytes. 

使用 -histo:live 查看内存中有哪些对象

jmap -histo:live 41565 > ~/jmap.txt  

Reference

https://docs.oracle.com/javase/8/docs/technotes/tools/unix/jmap.html

https://www.cnblogs.com/yjd_hycf_space/p/7753847.html