History

Pádraig Brady 0dd8071e2e pzstd: fix test failure on headless build Remove this test as pass/fail status is dependent on whether I/O is connected to a tty. It currrently passes on a tty but fails on a package build system for example.		2016-10-06 22:38:27 +01:00
..
images	Minor tweaks to pzstd graph	2016-09-01 17:53:23 -07:00
test	pzstd: fix test failure on headless build	2016-10-06 22:38:27 +01:00
utils	[pzstd] Spawn less threads in tests	2016-09-22 18:59:22 -07:00
.gitignore	zbufftest only depends on standard C time.h	2016-09-01 18:11:12 -07:00
ErrorHolder.h	Clean up compiler warnings + Build pzstd on travis	2016-09-02 12:23:49 -07:00
Makefile	[pzstd] Turn on warnings + quiet them	2016-09-22 16:12:29 -07:00
Options.cpp	Merge remote-tracking branch 'refs/remotes/facebook/dev' into zlibWrapper	2016-09-26 20:57:01 +02:00
Options.h	[pzstd] Make CLI compatible with zstd	2016-09-21 14:29:47 -07:00
Pzstd.cpp	[pzstd] Add status update for MB written	2016-09-23 15:47:26 -07:00
Pzstd.h	[pzstd] Add status update for MB written	2016-09-23 15:47:26 -07:00
README.md	[pzstd] Update README to reflect new CLI	2016-09-23 13:07:54 -07:00
SkippableFrame.cpp	Clean up compiler warnings + Build pzstd on travis	2016-09-02 12:23:49 -07:00
SkippableFrame.h	Add PZstandard to contrib/	2016-09-01 15:25:31 -07:00
main.cpp	[pzstd] Make CLI compatible with zstd	2016-09-21 14:29:47 -07:00

README.md

Parallel Zstandard (PZstandard)

Parallel Zstandard is a Pigz-like tool for Zstandard. It provides Zstandard format compatible compression and decompression that is able to utilize multiple cores. It breaks the input up into equal sized chunks and compresses each chunk independently into a Zstandard frame. It then concatenates the frames together to produce the final compressed output. Pzstandard will write a 12 byte header for each frame that is a skippable frame in the Zstandard format, which tells PZstandard the size of the next compressed frame. PZstandard supports parallel decompression of files compressed with PZstandard. When decompressing files compressed with Zstandard, PZstandard does IO in one thread, and decompression in another.

Usage

PZstandard supports the same command line interface as Zstandard, but also provies the -p option to specify the number of threads. Dictionary mode is not currently supported.

Basic usage

pzstd input-file -o output-file -p num-threads -#          # Compression
pzstd -d input-file -o output-file -p num-threads          # Decompression

PZstandard also supports piping and fifo pipes

cat input-file | pzstd -p num-threads -# -c > /dev/null

For more options

pzstd --help

PZstandard tries to pick a smart default number of threads if not specified (displayed in pzstd --help). If this number is not suitable, during compilation you can define PZSTD_NUM_THREADS to the number of threads you prefer.

Benchmarks

As a reference, PZstandard and Pigz were compared on an Intel Core i7 @ 3.1 GHz, each using 4 threads, with the Silesia compression corpus.

Compression Speed vs Ratio with 4 Threads	Decompression Speed with 4 Threads

The test procedure was to run each of the following commands 2 times for each compression level, and take the minimum time.

time pzstd -# -p 4    -c silesia.tar     > silesia.tar.zst
time pzstd -d -p 4    -c silesia.tar.zst > /dev/null

time pigz  -# -p 4 -k -c silesia.tar     > silesia.tar.gz
time pigz  -d -p 4 -k -c silesia.tar.gz  > /dev/null

PZstandard was tested using compression levels 1-19, and Pigz was tested using compression levels 1-9. Pigz cannot do parallel decompression, it simply does each of reading, decompression, and writing on separate threads.

Tests

Tests require that you have gtest installed. Modify GTEST_INC and GTEST_LIB in test/Makefile and utils/test/Makefile to work for your install of gtest. Then run make test in the contrib/pzstd directory.