Shitty Ruby Rack memory profiler

object_allocation_tracer.rb

require 'objspace'
require 'set'

class ObjectAllocationTracer
  include ObjectSpace

  def initialize(app)
    @app = app
    @sources = Set.new
    @traces = []
  end

  def call(env)
    output = nil
    trace_objects do
      output = @app.call(env)
    end
    dump_trace
    output
  end

  private

  def dump_trace
    CSV.open('object_trace.csv', 'wb', write_headers: true, headers: @sources.to_a << :id) do |csv|
      @traces.each_with_index do |trace, i|
        csv << trace.merge(id: i)
      end
    end
  end

  def trace_objects
    trace_object_allocations do
      yield
    end

    trace = each_object(String).each_with_object(Hash.new(0)) do |obj, t|
      file = allocation_sourcefile(obj)
      line = allocation_sourceline(obj)
      next if file.nil? || line.nil?
      source = "#{file}:#{line}".to_sym
      @sources << source
      t[source] += 1
    end

    @traces << trace
  end
end