jstat：OGC& OC，PGC&个人计算机 [英] jstat: difference between OGC & OC, PGC & PC

问题描述

我正在学习jstat，它可以告诉我关于JVM不同世代的信息。从 jstat文档，我了解新一代由伊甸园，s0和s1组成。例如，如果您对以下内容进行数学运算，您会看到NGC = EC + S0C + S1C。

  $ jstat -gccapacity -t 21830 5000 
时间戳NGCMN NGCMX NGC S0C S1C EC OGCMN OGCMX OGC OC PGCMN PGCMX PGC PC YGC FGC 
 248767.4 2624.0 87360.0 6656.0 640.0 640.0 5376.0 5376.0 174784.0 12840.0 12840.0 21248.0 131072.0 34304.0 34304.0 457 73 
 248772.4 2624.0 87360.0 6656.0 640.0 640.0 5376.0 5376.0 174784.0 12840.0 12840.0 21248.0 131072.0 34304.0 34304.0 457 73 
 248777.3 2624.0 87360.0 6656.0 640.0 640.0 5376.0 5376.0 174784.0 12840.0 12840.0 21248.0 131072.0 34304.0 34304.0 457 73 
  

I' m想知道有什么区别：

• OGC（当前旧容量（KB））和
  
• OC（当前旧空间容量（KB））。

同样适用于：

• PGC （当前固定发电容量（KB））和
  
• 个人电脑（当前固定容量（KB））。
  
  
  

  每对货币都有相同的价值，至少对我来说，现在。旧的空间旁边有没有任何东西？

  
  
  

  ---

  
  编辑：我不认为有什么区别，
  

  解决方案

  我只是寻求jdk源码
  
  

  简而言之：
  OGC = sum（all OC）

  
  
  

  可能包含超过一个空格。
  
  然而，Hotspot旧有只有1个空间（年轻的gen有3：eden，s0和s1），
  jstat显示它们的价值相同。
  
  什么是OC和OGC

  
  
  

  from
  jdk / src / share / classes / sun / tools / jstat / resources / jstat_options
  $ b

  OGC = sun.gc.generation.1.capacity

  
  
  

  OC = sun.gc.generation.1.space.0.capacity

   专栏{
   header'^ OGC ^/ *旧一代容量 - 当前* / 
  数据sun.gc.generation.1.capaci ty 
   scale K 
   align right 
   width 11 
   format0.0
  } 
   column {
   header^ OC ^/ *旧空间容量 - 当前* / 
  数据sun.gc.generation.1.space.0.capacity 
  比例K 
  右对齐
  宽度11 
  格式0.0 
  
    

  GEN.1中的多少空间

  
  
  

  运行下面的groovy代码来检查
  
  

    import java.lang.management .ManagementFactory 
   import sun.jvmstat.monitor。*; 
   
   name = ManagementFactory.runtimeMXBean.name 
   pid = name [0 ..< name.indexOf（'@'）] 
   vmId = new VmIdentifier（pid）
   vm = MonitoredHost.getMonitoredHost（vmId）.getMonitoredVm（vmId，0）
   
   println'Y count：'+ vm.findByName（'sun.gc.generation.0.spaces'）。longValue （）
   println'O count：'+ vm.findByName（'sun.gc.generation.1.spaces'）。longValue（）
    

  输出为：
  
  

    Y计数：3 
   O计数： 1 
    

  您可以对GEN.2（PERM GEN）进行同样的操作

  
  

  I'm learning about jstat and what it can tell me about the JVM's different generations. From the jstat docs I understand the new gen is made up of eden, s0 and s1. For example, if you do the math on the following, you see that NGC = EC + S0C + S1C. Great stuff.

  $ jstat -gccapacity -t 21830 5000
  Timestamp        NGCMN    NGCMX     NGC     S0C   S1C       EC      OGCMN      OGCMX           OGC         OC      PGCMN    PGCMX     PGC       PC     YGC    FGC 
         248767.4   2624.0  87360.0   6656.0  640.0  640.0   5376.0     5376.0   174784.0    12840.0    12840.0  21248.0 131072.0  34304.0  34304.0    457    73
         248772.4   2624.0  87360.0   6656.0  640.0  640.0   5376.0     5376.0   174784.0    12840.0    12840.0  21248.0 131072.0  34304.0  34304.0    457    73
         248777.3   2624.0  87360.0   6656.0  640.0  640.0   5376.0     5376.0   174784.0    12840.0    12840.0  21248.0 131072.0  34304.0  34304.0    457    73
  

  I'm wondering what's the difference between:

  • OGC (Current old generation capacity (KB)) and
  • OC (Current old space capacity (KB)).

  And similarly for:

  • PGC (Current Permanent generation capacity (KB)) and
  • PC (Current Permanent space capacity (KB)).

  Each pair has the same value, at least for me, right now. Is there ever anything in the old generation beside the old space?

  ---

  Edit: I don't think there is a difference, but I'll leave this question up just in case.

  解决方案

  I just seek from the jdk source

  in short: OGC = sum(all OC)

  A gen may contain MORE THAN ONE spaces.

  However, Hotspot old gen has only 1 space ( young gen has 3: eden , s0 and s1 ), jstat shows the same value for them.

  WHAT IS OC and OGC

  from jdk/src/share/classes/sun/tools/jstat/resources/jstat_options

  I got

  OGC = sun.gc.generation.1.capacity

  OC = sun.gc.generation.1.space.0.capacity

    column {
      header "^OGC^"  /* Old Generation Capacity - Current */
      data sun.gc.generation.1.capacity
      scale K
      align right
      width 11
      format "0.0"
    }
    column {
      header "^OC^"   /* Old Space Capacity - Current */
      data sun.gc.generation.1.space.0.capacity
      scale K
      align right
      width 11
      format "0.0"
    }
  

  HOW MANY SPACES IN GEN.1

  run groovy code below to examine

  import java.lang.management.ManagementFactory
  import sun.jvmstat.monitor.*;
  
  name = ManagementFactory.runtimeMXBean.name
  pid  = name[0..<name.indexOf('@')]
  vmId = new VmIdentifier(pid)
  vm   = MonitoredHost.getMonitoredHost(vmId).getMonitoredVm(vmId, 0)
  
  println 'Y count :' + vm.findByName('sun.gc.generation.0.spaces').longValue()
  println 'O count :' + vm.findByName('sun.gc.generation.1.spaces').longValue()
  

  output is:

  Y count :3
  O count :1
  

  You can do the same for GEN.2 (PERM GEN)

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