This is Perl module Data::WeightedRoundRobin. INSTALLATION Data::WeightedRoundRobin installation is straightforward. If your CPAN shell is set up, you should just be able to do % cpan Data::WeightedRoundRobin Download it, unpack it, then build it as per the usual: % perl Makefile.PL % make && make test Then install it: % make install DOCUMENTATION Data::WeightedRoundRobin documentation is available as in POD. So you can do: % perldoc Data::WeightedRoundRobin to read the documentation online with your favorite pager. xaicron