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?
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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.
Since p7zip version 9.04, you can use lzma2 to compress in Parallel.
7za a -m0=lzma2 archive.7z directory