measure_gc.rb

class MeasureGC
  def self.run(options = { gc: :enable })
    if options[:gc] == :disable
      GC.disable
    elsif options[:gc] == :enable
      # collect memory allocated during library loading
      # and our own code before the measurement
      GC.start
      GC.start
      GC.start
    end

    memory_before = `ps -o rss= -p #{Process.pid}`.to_i / 1024
    gc_stat_before = GC.stat

    time = Benchmark.realtime do
      yield
    end

    gc_stat_after = GC.stat

    if options[:gc] == :enable
      GC.start
      GC.start
      GC.start
    end

    memory_after = `ps -o rss= -p #{Process.pid}`.to_i / 1024

    puts({
      RUBY_VERSION => {
        gc: options[:gc],
        time: time.round(2),
        total_allocated_objects: gc_stat_after[:total_allocated_objects].to_i - gc_stat_before[:total_allocated_objects].to_i,
        total_freed_objects: gc_stat_after[:total_freed_objects].to_i - gc_stat_before[:total_freed_objects].to_i,
        gc_count: gc_stat_after[:count].to_i - gc_stat_before[:count].to_i,
        memory: format('%d MB', (memory_after - memory_before))
      }
    }.to_json)
  end
end