MemoryProfiler

module MemoryProfiler
  class << self
    DEFAULTS = {:delay => 10, :string_debug => false}

    def start(opt={})
      opt = DEFAULTS.dup.merge(opt)

      Thread.new do
        prev = Hash.new(0)
        curr = Hash.new(0)
        curr_strings = []
        delta = Hash.new(0)

        file = File.open('log/memory_profiler.log','w')

        loop do
          begin
            GC.start
            curr.clear

            curr_strings = [] if opt[:string_debug]

            ObjectSpace.each_object do |o|
              curr[o.class] += 1 #Marshal.dump(o).size rescue 1
              if opt[:string_debug] and o.class == String
                curr_strings.push o
              end
            end

            if opt[:string_debug]
              File.open("log/memory_profiler_strings.log.#{Time.now.to_i}",'w') do |f|
                curr_strings.sort.each do |s|
                  f.puts s
                end
              end
              curr_strings.clear
            end

            delta.clear
            (curr.keys + delta.keys).uniq.each do |k,v|
              delta[k] = curr[k]-prev[k]
            end

            file.puts "Top 20"
            delta.sort_by { |k,v| -v.abs }[0..19].sort_by { |k,v| -v}.each do |k,v|
              file.printf "%+5d: %s (%d)\n", v, k.name, curr[k] unless v == 0
            end
            file.flush

            delta.clear
            prev.clear
            prev.update curr
            GC.start
          rescue Exception => err
            STDERR.puts "** memory_profiler error: #{err}"
          end
          sleep opt[:delay]
        end
      end
    end
  end
end