I'm looking to use lbzip2 instead of standard bzip2, in order to gain the advantages of multiple CPU cores being used for compression. Standard bzip2 only uses one core even on a multicore machine which means we don't take advantage of the CPU power anything even remotely modern. lbzip2 is otherwise a drop in replacement for bzip2, that does support multi core compression. However to do this we need to pass the --with-bzip2= flag to ./configure: http://www.gnu.org/software/tar/manual/html_node/lbzip2.html This RFE is to have lbzip2 and pbzip2 USE flag support added to the tar ebuild so that tar will be able to find and use these compression applications as well.
we're not going to add USE flags just to set --with-bzip2/etc... to different values at runtime. you can use per-package env to set EXTRA_ECONF on your own system. what might make sense is to have a wrapper and tell tar to run that, and the wrapper will select on the fly from a suite of possible tools. but neither of these options are preventing you from doing: lbzip2 -dc foo.tar.bz2 | tar xf - or: tar -I lbzip2 -xf foo.tar.bz2
Use EXTRA_ECONF for tar or use app-alternatives.
