Displays memory statistics. Interpretation of memory usage statistics are beyond the scope of this document. For display purposes, some of the repetitive portions of the examples have been omitted.

Memory alone provides a simple display.

memory max 65088K used 9336K, free 464K,
      nodes: total allocated 7441 namespace 3604
      Maps: funcs 0, xpath 0
      Heap: init 0K, used 8932K, commit 9336K, max 65088K
      Non-Heap: init 28864K, used 22852K, commit 32096K, max 118784K
      Garbage Collection Info
      Name: Copy   Collection count: 203   time: 454ms
      Name: MarkSweepCompact   Collection count: 0   time: 0ms

Memory detail yields a far more complete display.

memory max 65088K used 9336K, free 899K,
      nodes: total allocated 7441 namespace 3604
      Maps: funcs 0, xpath 0
      Heap: init 0K, used 8438K, commit 9336K, max 65088K
      Non-Heap: init 28864K, used 22860K, commit 32096K, max 118784K
      Garbage Collection Info
      Name: Copy   Collection count: 204   time: 455ms
         Memory Pools:
           Eden Space
           Survivor Space
      Name: MarkSweepCompact   Collection count: 0   time: 0ms
         Memory Pools:
           Eden Space
           Survivor Space
           Tenured Gen
           Perm Gen
           Perm Gen [shared-ro]
      Memory Pools Info
      Name: Code Cache
           Usage: init 192K, used 1613K, commit 1632K, max 32768K
           Peak Usage: init 192K, used 1613K, commit 1632K, max 32768K
           Type: Non-heap memory
           Memory Manager Names: CodeCacheManager
      Name: Eden Space
                -
                -
      Name: Perm Gen [shared-rw]
        Usage: init 12288K, used 5821K, commit 12288K, max 12288K
        Collection Usage: init 12288K, used 0K, commit 0K, max 12288K
        Peak Usage: init 12288K, used 5821K, commit 12288K, max 12288K
        Type: Non-heap memory
        Memory Manager Names: MarkSweepCompact

Java memory is under control of the system, and generally falls into four major categories.

Field	Definition
init	Represents the initial amount of memory (in bytes) that the Java virtual machine requests from the operating system for memory management during startup. The Java virtual machine may request additional memory from the operating system and may also release memory to the system over time. The value of init may be undefined (0) on some platforms.
used	Represents the amount of memory currently used.
committed	Represents the amount of memory (in bytes) that is guaranteed to be available for use by the Java virtual machine. The amount of committed memory may change over time (increase or decrease). The Java virtual machine may release memory to the system and committed could be less than init. Committed will always be greater than or equal to used.
max	Represents the maximum amount of memory (in bytes) that can be used for memory management. Its value may be undefined. The maximum amount of memory may change over time if defined. The amount of used and committed memory will always be less than or equal to max if max is defined. A memory allocation may fail if it attempts to increase the used memory such that used > committed even if used <= max would still be true (for example, when the system is low on virtual memory).