jmap heap输出各项参数解释

迈不过友情╰ 2023-03-03 13:27 16阅读 0赞

jmap -heap 21168
    
    Attaching to process ID 21168, please wait...
    
    Debugger attached successfully.
    
    Server compiler detected.
    
    JVM version is 25.92-b14
    
    
    
    using thread-local object allocation.
    
    Parallel GC with 4 thread(s)     #4个gc线程 
    
    
    
    Heap Configuration:
    
       MinHeapFreeRatio         = 0   #-XX:MinHeapFreeRatio设置JVM堆最小空闲比率  
    
       MaxHeapFreeRatio         = 100 #-XX:MaxHeapFreeRatio设置JVM堆最大空闲比率
    
       MaxHeapSize              = 4294967296 (4096.0MB) #-XX:MaxHeapSize=设置JVM堆的最大大小  
    
       NewSize                  = 89128960 (85.0MB) #-XX:NewSize=设置JVM堆的‘新生代’的默认大小  
    
       MaxNewSize               = 1431306240 (1365.0MB)  #-XX:MaxNewSize=设置JVM堆的‘新生代’的最大大小 
    
       OldSize                  = 179306496 (171.0MB) #-XX:OldSize=设置JVM堆的‘老年代’的大小  
    
       NewRatio                 = 2 #-XX:NewRatio=:‘新生代’和‘老年代’的大小比率  
    
       SurvivorRatio            = 8 #-XX:SurvivorRatio=设置年轻代中Eden区与Survivor区的大小比值  
    
       MetaspaceSize            = 21807104 (20.796875MB)  # jdk8中tomcat修改配置PermSize为MetaspaceSize，Metaspace扩容时触发FullGC的初始化阈值，也是最小的阈值
    
       CompressedClassSpaceSize = 1073741824 (1024.0MB) #maximum size of class area in Metaspace when compressed class poniters are used
    
       MaxMetaspaceSize         = 17592186044415 MB # Metaspac的最大大小
    
       G1HeapRegionSize         = 0 (0.0MB) # size of the G1 regions
    
    
    
    Heap Usage:
    
    PS Young Generation
    
    Eden Space: #Eden区内存分布  
    
       capacity = 67108864 (64.0MB) #容量
    
       used     = 1342200 (1.2800216674804688MB) #已经使用大小
    
       free     = 65766664 (62.71997833251953MB) #剩余容量
    
       2.0000338554382324% used #使用比例
    
    From Space: #其中一个Survivor区的内存分布  
    
       capacity = 11010048 (10.5MB)
    
       used     = 0 (0.0MB)
    
       free     = 11010048 (10.5MB)
    
       0.0% used
    
    To Space:#另外一个Survivor区的内存分布  
    
       capacity = 11010048 (10.5MB)
    
       used     = 0 (0.0MB)
    
       free     = 11010048 (10.5MB)
    
       0.0% used
    
    PS Old Generation  #当前的Old区内存分布  
    
       capacity = 68681728 (65.5MB)
    
       used     = 1232944 (1.1758270263671875MB)
    
       free     = 67448784 (64.32417297363281MB)
    
       1.7951557654460877% used
    
    
    
    2221 interned Strings occupying 147448 bytes.
    
    
    作者：Jimin
    链接：https://www.imooc.com/article/43987
    来源：慕课网
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