#17 Parallel compress

closed
nobody
None
5
2009-06-07
2007-10-23
l1t
No

I saw compression.ca/pbzip2/ is a Parallel BZIP2 ,
did 7z use the same technolgy?
and why LZMA or zip format can't use Parallel compress?

Discussion

  • my space

    my space - 2007-10-23

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    > I saw compression.ca/pbzip2/ is a Parallel BZIP2 ,

    7z can compress BZIP2 using several CPU.

    > did 7z use the same technolgy?
    > and why LZMA or zip format can't use Parallel compress?

    The BZIP2 format compress a file block by block (900kB),
    so it is easy to compress each block in parallel.

    For zip format, a program can compress each file in parallel.
    (but for one big file, it is not easy to compress in parallel without
    lose some compression ratio).

    For 7z format, to have a better compression ratio, all the files
    are put together before compressing.
    So it's difficult to compress in parallel.

    Now, 7z can use 2 CPU.

     
  • my space

    my space - 2009-06-07
    • status: open --> closed
     
  • my space

    my space - 2009-06-07

    Since p7zip version 9.04, you can use lzma2 to compress in Parallel.

    7za a -m0=lzma2 archive.7z directory

     

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