Look for a single generation of ruby heap and print out the allocation source.

analyze-gen.rb

require 'json'
class Analyzer
  def initialize(filename)
    @filename = filename
  end

  def analyze
    data = []
    File.open(@filename) do |f|
        f.each_line do |line|
          parsed=JSON.parse(line)
          data << parsed if parsed["generation"] == ARGV[1].to_i
        end
    end
    data.group_by{|row| "#{row["file"]}:#{row["line"]}"}
        .sort{|a,b| b[1].count <=> a[1].count}
        .each do |k,v|
          puts "#{k} * #{v.count}"
        end
  end
end

Analyzer.new(ARGV[0]).analyze