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  1. JDK
  2. JDK-8215027

Unmap the NIO file mappings with MapMode.PRIVATE on Linux before dumping a corefile.

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      The proposed fix of JDK-8200613 causes an increase in the size of the corefile dumped with CDS on Linux.
      The typical corefile size increase with this would include the following components at a high level:
      * Any NIO file mapping with MapMode.PRIVATE.
      * Any file mmap()-ed by any native library with MAP_PRIVATE.
      * The read only CDS regions (ro and od): Of the order of a few MB.
      * The shared strings CDS region. (typically less than 1 MB).
      * 2 MB per native shared library (regions with ---p permissions
      mapped by the dynamic linker for better alignment and for keeping
      libraries efficiently shareable).
      * The JDK 'modules' file. (About 140 MB).

      To control the increase in the corefile size, the modules file is being unmapped as a part of the proposed fix for JDK-8200613.
      We need to unmap the NIO file mappings with MapMode.PRIVATE too.

            Unassigned Unassigned
            jgeorge Jini George (Inactive)
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