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  1. Lucene - Core
  2. LUCENE-1743

MMapDirectory should only mmap large files, small files should be opened using SimpleFS/NIOFS

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    • Improvement
    • Status: Open
    • Major
    • Resolution: Unresolved
    • 2.9
    • 4.9, 6.0
    • core/store
    • New

    Description

      This is a followup to LUCENE-1741:
      Javadocs state (in FileChannel#map): "For most operating systems, mapping a file into memory is more expensive than reading or writing a few tens of kilobytes of data via the usual read and write methods. From the standpoint of performance it is generally only worth mapping relatively large files into memory."
      MMapDirectory should get a user-configureable size parameter that is a lower limit for mmapping files. All files with a size<limit should be opened using a conventional IndexInput from SimpleFS or NIO (another configuration option for the fallback?).

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            uschindler Uwe Schindler
            uschindler Uwe Schindler
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              Created:
              Updated: