Plzip is a massively parallel (multi-threaded) lossless data compressor
based on the lzlib compression library, with a user interface similar to
the one of lzip, bzip2 or gzip.
Plzip can compress/decompress large files on multiprocessor machines
much faster than lzip, at the cost of a slightly reduced compression
ratio. Note that the number of usable threads is limited by file size;
on files larger than a few GB plzip can use hundreds of processors, but
on files of only a few MB plzip is no faster than lzip.
When compressing, plzip divides the input file into chunks and
compresses as many chunks simultaneously as worker threads are chosen,
creating a multi-member compressed file.
When decompressing, plzip decompresses as many members simultaneously as
worker threads are chosen. Files that were compressed with lzip will not
be decompressed faster than using lzip (unless the "-b" option was used)
because lzip usually produces single-member files, which can't be
decompressed in parallel.
In this plzip benchmark page you can
find some tests showing the performance of plzip on a multiprocessor
Plzip uses the lzip file format; the files produced by plzip are fully
compatible with lzip-1.4 or newer, and can be rescued with lziprecover.
The lzip file format is designed for data sharing and long-term
archiving, taking into account both data integrity and decoder
The lzip format provides very safe integrity checking and some data
recovery means. The lziprecover program
can repair bit-flip errors (one of the most common forms of data
corruption) in lzip files, and provides data recovery capabilities,
including error-checked merging of damaged copies of a file.
The lzip format is as simple as possible (but not simpler). The lzip
manual provides the code of a simple decompressor along with a detailed
explanation of how it works, so that with the only help of the lzip
manual it would be possible for a digital archaeologist to extract the
data from a lzip file long after quantum computers eventually render
Additionally the lzip reference implementation is copylefted, which
guarantees that it will remain free forever.
A nice feature of the lzip format is that a corrupt byte is easier to
repair the nearer it is from the beginning of the file. Therefore, with
the help of lziprecover, losing an entire archive just because of a
corrupt byte near the beginning is a thing of the past.
Plzip uses the same well-defined exit status values used by lzip and
bzip2, which makes it safer than compressors returning ambiguous warning
values (like gzip) when it is used as a back end for other programs like
tar or zutils.
Learn more about lzip in the Lzip Home Page.
The manual is available in the info system of the GNU
Operating System. Use info to access the top level info
page. Use info plzip to access the plzip section directly.
An online manual for plzip can be found
The latest released version of plzip can be found
You may also subscribe to
and receive an email every time a new version is released.
Hannes Domani kindly provided a Windows port of plzip that can also be
downloaded from the Savannah download link just above.
How to get help
For general discussion of bugs in plzip the mailing list
is the most appropriate forum. Please send messages as plain text.
Please do not send messages encoded as HTML nor encoded as base64 MIME
nor included as multiple formats. Please include a descriptive subject
line. If all of the subject are "bug in plzip" it is impossible to
An archive of the bug report mailing list is available at
How to help
To contact the author, either to report a bug or to contribute fixes or
improvements, send mail to
Please send messages as plain text. If posting patches they should be in
unified diff format against the latest version. They should include a
See also the lzip
project page at Savannah.
Plzip is free software: you can redistribute it and/or modify it under
the terms of the GNU General Public License as published by the Free
Software Foundation, either version 2 of the License, or (at your
option) any later version.
Copyright © 2014 Antonio Diaz Diaz
Lzip logo Copyright © 2013 Sonia Diaz Pacheco
You are free to copy, modify and distribute all or part of this article