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pigz (parallel implementation of gzip) is a fully functional replacement for gzip that exploits multiple processors and multiple cores when compressing data. pigz is extremely helpful when compacting a large directory. unpigz (equivalent to 'gunzip') is used to uncompress gzip'ed file and unpigz utilizes only one thread.

pigz can be accessed by loading a pigz module (run "module spider pigz" to find the module name). On FTN nodes, pigz is available without loading the module.

Simple examples

  • Compress a file
pigz my_file
  • Compress a file with best compression rate
pigz -9 my_file
pigz --best my_file
  • Uncompress
unpigz my_file.gz
  • Specify number of threads ('-p no_thread'). The number of compress threads is set by default to the number of online processors.
pigz -9 -p 10 my_big_file

Using tar with pigz

  • specify compress program for tar
tar -I pgz cf my_dir.tar.gz my_dir/
tar --use=compress-program pigz my_dir.tar.gz my_dir/
  • specify more options with pigz
tar cf - my_dir/ | pigz -9 > my_dir.tgz
tar cf - my_dir1 my_dir2 | pigz -9 -p 15 > my_backup.tgz

Speed comparison

The following example shows speed difference between gzip and pigz on CentOS 7 ISO file (~ 11GB) on Terra server (28 cores, 2.4 GHz, with hyper-thread enabled). The time for best compression (-9) was about 27 sec (pigz) vs 6 min 6 sec (gzip), where pigz was about 13 times faster than gzip. pigz used 58 threads with 2361% CPU, which was equivalent to 2.361 cores (out of 28 cores).

$ ls -l *.iso
-rw-rw-r--  1 user1 user1 11026825216 Dec 16 12:26 CentOS-7-x86_64-Everything-1908.iso

$ time gzip -9 CentOS-7-x86_64-Everything-1908.iso
real    6m6.302s
user    5m51.763s
sys     0m27.914s

$ time pigz -9 CentOS-7-x86_64-Everything-1908.iso
real    0m26.987s
user    9m9.098s
sys     0m19.994s

$ ls -l *.iso.gz
-rw-rw-r--  1 user1 user1 10653982882 Dec 16 12:26 CentOS-7-x86_64-Everything-1908.iso.gz


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