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问题来源:https://docs.oracle/javase/8/docs/technotes/guides/vm/gctuning/considerations.html

问题详情:Example 11-1 Typical Heap Printout

Heap
  PSYoungGen      total 10752K, used 4419K
    [0xffffffff6ac00000, 0xffffffff6b800000, 0xffffffff6b800000)
    eden space 9216K, 47% used
      [0xffffffff6ac00000,0xffffffff6b050d68,0xffffffff6b500000)
    from space 1536K, 0% used
      [0xffffffff6b680000,0xffffffff6b680000,0xffffffff6b800000)
    to   space 1536K, 0% used
      [0xffffffff6b500000,0xffffffff6b500000,0xffffffff6b680000)
  ParOldGen       total 20480K, used 20011K
      [0xffffffff69800000, 0xffffffff6ac00000, 0xffffffff6ac00000)
    object space 20480K, 97% used 
      [0xffffffff69800000,0xffffffff6ab8add8,0xffffffff6ac00000)
  Metaspace       used 2425K, capacity 4498K, committed 4864K, reserved 1056768K
    class space   used 262K, capacity 386K, committed 512K, reserved 1048576K

In the line beginning with Metaspace, the used value is the amount of space used for loaded classes. The capacity value is the space available for metadata in currently allocated chunks. The committed value is the amount of space available for chunks. The reserved value is the amount of space reserved (but not necessarily committed) for metadata. The line beginning with class space line contains the corresponding values for the metadata for compressed class pointers.


问题:

  1. 在这段gc日志中,metaspace和class space分别代表什么?
  2. metaspace和class space的日志统计信息中used、capacity、committed、reserved是什么意思?

本文标签: CapacityJVMReservedcommited