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  1. JDK
  2. JDK-8221896

Uncommit space on memory mapped heaps

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    • Resolution: Unresolved
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      Since kernel 2.6.38 Linux has the capability to "uncommit" space in memory mapped files (FALLOC_FL_PUNCH_HOLE, http://man7.org/linux/man-pages/man2/fallocate.2.html).

      This would allow collectors mapping the Java heap from a file (via e.g. AllocateHeapAt) for e.g. providing Java heap on NVDIMM uncommit unused space.

      ZGC will also use this facility planned with JEP 351: ZGC: Uncommit Unused Memory, however it is useful for all collectors.

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            tschatzl Thomas Schatzl
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