Class: Rack::MiniProfiler::GCProfiler

Inherits:
Object
  • Object
show all
Defined in:
lib/mini_profiler/gc_profiler.rb

Instance Method Summary collapse

Constructor Details

#initialize ⇒ GCProfiler

Returns a new instance of GCProfiler.



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# File 'lib/mini_profiler/gc_profiler.rb', line 5

def initialize
  @ignore = []
  @ignore << @ignore.__id__
end

Instance Method Details

#analyze_growth(ids_before, ids_after) ⇒ Object 



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# File 'lib/mini_profiler/gc_profiler.rb', line 63

def analyze_growth(ids_before, ids_after)
  new_objects = 0
  memory_allocated = 0

  ids_after.each do |id, _|
    if !ids_before.include?(id) && obj = ObjectSpace._id2ref(id)
      # this is going to be version specific (may change in 2.1)
      size = ObjectSpace.memsize_of(obj)
      memory_allocated += size
      new_objects += 1
    end
  end

  [new_objects, memory_allocated]
end

#analyze_initial_state(ids_before) ⇒ Object 



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# File 'lib/mini_profiler/gc_profiler.rb', line 79

def analyze_initial_state(ids_before)
  memory_allocated = 0
  objects = 0

  ids_before.each do |id, _|
    if obj = ObjectSpace._id2ref(id)
      # this is going to be version specific (may change in 2.1)
      memory_allocated += ObjectSpace.memsize_of(obj)
      objects += 1
    end
  end

  [objects, memory_allocated]
end

#analyze_strings(ids_before, ids_after) ⇒ Object 



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# File 'lib/mini_profiler/gc_profiler.rb', line 51

def analyze_strings(ids_before, ids_after)
  result = {}
  ids_after.each do |id, _|
    obj = ObjectSpace._id2ref(id)
    if String === obj && !ids_before.include?(obj.object_id)
      result[obj] ||= 0
      result[obj] += 1
    end
  end
  result
end

#diff_object_stats(before, after) ⇒ Object 



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# File 'lib/mini_profiler/gc_profiler.rb', line 39

def diff_object_stats(before, after)
  diff = {}.compare_by_identity
  after.each do |k, v|
    diff[k] = v - before[k]
  end
  before.each do |k, v|
    diff[k] = 0 - v unless after.has_key?(k)
  end

  diff
end

#object_space_stats ⇒ Object 



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# File 'lib/mini_profiler/gc_profiler.rb', line 10

def object_space_stats
  stats = Hash.new(0).compare_by_identity
  ids = Hash.new.compare_by_identity

  @ignore << stats.__id__
  @ignore << ids.__id__

  ObjectSpace.each_object { |o|
    begin
      stats[o.class] += 1
      ids[o.__id__] = o if Integer === o.__id__
    rescue NoMethodError
      # protect against BasicObject
    end
  }

  @ignore.each do |id|
    if ids.delete(id)
      klass = ObjectSpace._id2ref(id).class
      stats[klass] -= 1
    end
  end

  result = { stats: stats, ids: ids }
  @ignore << result.__id__

  result
end

#profile_gc(app, env) ⇒ Object 



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# File 'lib/mini_profiler/gc_profiler.rb', line 94

def profile_gc(app, env)

  # for memsize_of
  require 'objspace'

  # clean up before
  GC.start
  stat          = GC.stat
  prev_gc_state = GC.disable
  stat_before   = object_space_stats
  b             = app.call(env)[2]
  b.close if b.respond_to? :close
  stat_after = object_space_stats
  # so we don't blow out on memory
  prev_gc_state ? GC.disable : GC.enable

  diff                          = diff_object_stats(stat_before[:stats], stat_after[:stats])
  string_analysis               = analyze_strings(stat_before[:ids], stat_after[:ids])
  new_objects, memory_allocated = analyze_growth(stat_before[:ids], stat_after[:ids])
  objects_before, memory_before = analyze_initial_state(stat_before[:ids])

  body = []

  body << "
Overview
--------
Initial state: object count: #{objects_before}
Memory allocated outside heap (bytes): #{memory_before}

GC Stats:
--------
#{stat.map { |k, v| "#{k} : #{v}" }.sort!.join("\n")}

New bytes allocated outside of Ruby heaps: #{memory_allocated}
New objects: #{new_objects}
"

  body << "
ObjectSpace delta caused by request:
-----------------------------------\n"
  diff.to_a.delete_if { |_k, v| v == 0 }.sort_by! { |_k, v| v }.reverse_each do |k, v|
    body << "#{k} : #{v}\n"
  end

  body << "\n
ObjectSpace stats:
-----------------\n"

  stat_after[:stats].to_a.sort_by! { |_k, v| v }.reverse_each do |k, v|
    body << "#{k} : #{v}\n"
  end

  body << "\n
String stats:
------------\n"

  string_analysis.to_a.sort_by! { |_k, v| -v }.take(1000).each do |string, count|
    body << "#{count} : #{string}\n"
  end

  [200, { 'Content-Type' => 'text/plain' }, body]
ensure
  prev_gc_state ? GC.disable : GC.enable
end