def self.in_even_groups_by_size(items_with_sizes, num_groups, options={})
groups = Array.new(num_groups){{:items => [], :size => 0}}
(options[:single_process]||[]).each do |pattern|
matched, items_with_sizes = items_with_sizes.partition{|item, size| item =~ pattern }
smallest = smallest_group(groups)
matched.each{|item,size| add_to_group(smallest, item, size) }
end
smallest_first(items_with_sizes).each do |item, size|
smallest = smallest_group(groups)
add_to_group(smallest, item, size)
end
groups.map!{|g| g[:items].sort }
end