jvm中命令jmap -heap字段代表的意思?_jvm jmap命令中的regions的含义-优快云博客

本文链接：https://blog.youkuaiyun.com/weixin_45810161/article/details/124894914

本文详细解析了JVM内存结构，包括堆内存配置、新生代与老年代的分配比例，以及Mark Sweep Compact GC过程。特别关注了Metaspace的使用和限制，有助于理解Java应用内存管理的关键细节。

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Attaching to process ID 30012, please wait...
Debugger attached successfully.
Server compiler detected.
JVM version is 25.281-b09

using thread-local object allocation.
Mark Sweep Compact GC

Heap Configuration:
   MinHeapFreeRatio         = 40        --空闲堆空间的最小百分比
   MaxHeapFreeRatio         = 70        --空闲堆空间的最大百分比
   MaxHeapSize              = 455081984 (434.0MB)  --堆空间的允许最大值
   NewSize                  = 9764864 (9.3125MB)   --新生代堆空间的默认值
   MaxNewSize               = 151650304 (144.625MB) --新生代堆空间的最大值
   OldSize                  = 19595264 (18.6875MB)  --老年代堆空间默认值
   NewRatio                 = 2                     --新生代老年代的空间比值,两个s区和eden区与老年代的空间比值,新生代:老年代=1:2
   SurvivorRatio            = 8                     --两个s区与Eden区的堆空间比值8 表示为8:1:10
   MetaspaceSize            = 21807104 (20.796875MB) --元空间的默认值
   CompressedClassSpaceSize = 1073741824 (1024.0MB)  --元空间的最大值
   MaxMetaspaceSize         = 17592186044415 MB
   G1HeapRegionSize         = 0 (0.0MB)             --表示使用G1回收算法的时候,jvm会将Heap空间分为若干个region,表示每个region的大小

Heap Usage:
New Generation (Eden + 1 Survivor Space):            --新生代
   capacity = 22740992 (21.6875MB)
   used     = 11725584 (11.182388305664062MB)
   free     = 11015408 (10.505111694335938MB)
   51.56144463706772% used
Eden Space:                                          --伊甸园区
   capacity = 20250624 (19.3125MB)
   used     = 10347424 (9.868072509765625MB)
   free     = 9903200 (9.444427490234375MB)
   51.096815584546924% used
From Space:                                  
   capacity = 2490368 (2.375MB)                    --s1区
   used     = 1378160 (1.3143157958984375MB)
   free     = 1112208 (1.0606842041015625MB)
   55.33961245888158% used
To Space:                                           --s2区
   capacity = 2490368 (2.375MB)
   used     = 0 (0.0MB)
   free     = 2490368 (2.375MB)
   0.0% used
tenured generation:                              --老年代
   capacity = 50413568 (48.078125MB)
   used     = 40039616 (38.18475341796875MB)
   free     = 10373952 (9.89337158203125MB)
   79.4223015518362% used

25885 interned Strings occupying 3178016 bytes.