640K ought to be enough for anybody, or how to use less memory in Ruby.

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640K ought to be enough for anybody, or how to use less memory in Ruby Julia Egorova, Back-end developer at JetRockets

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Julia Egorova github.com/vankiru twitter.com/vankiru vk.com/vankiru

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640k outght to be enough for anybody. » « Bill Gates, 1981

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I've said some stupid things and some wrong things, but not that. » « Bill Gates, 1996

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How much is 640K?

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How much is 640K?

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How much is 640K?

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What about Ruby?

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What about Ruby? Framework Memory Ruby On Rails ~ 60MB Hanami ~ 50MB Sinatra ~ 16MB Roda ~ 15MB

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What about Rails? Method Memory Rocket.find(1) ~ 650KB rocket.save ~ 100KB number_to_currency(100) ~ 11KB stylesheet_link_tag("rocket.css") ~ 3Kb

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How does Ruby memory work?

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Garbage Collection

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Garbage Collection Mark and Sweep

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Free List

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Free List

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Free List

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Free List

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Mark Phase

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Mark Phase

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Mark Phase

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Mark Phase

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Mark Phase

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Mark Phase

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Sweep Phase

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Sweep Phase

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Sweep Phase

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Generational GC

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Generational GC

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Generational GC

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Generational GC

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Generational GC

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Generational GC

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Generational GC

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Generational GC

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Generational GC

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Generational GC

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Generational GC

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Generational GC

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Ruby Memory Structure

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Heap Pages and Slots

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Heap Pages and Slots

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Heap Pages and Slots

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Heap Pages and Slots

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Heap Pages and Slots

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Heap Pages and Slots

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Tiny, Small and Large Objects RValue

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Tiny, Small and Large Objects VALUE *ptr → RValue

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Tiny, Small and Large Objects VALUE *ptr → RValue typedef uintptr_t VALUE;

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Tiny, Small and Large Objects

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Tiny, Small and Large Objects

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Tiny, Small and Large Objects

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Tiny, Small and Large Objects

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Tiny, Small and Large Objects

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Tiny, Small and Large Objects

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Tiny, Small and Large Objects

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Tiny, Small and Large Objects

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Tiny, Small and Large Objects

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Tiny, Small and Large Objects

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Tiny, Small and Large Objects

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Tiny, Small and Large Objects

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Tiny, Small and Large Objects

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How to proﬁle memory usage?

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Ruby Memory Proﬁling GC ObjectSpace memory_profiler get_process_mem derailed_benchmarks • • • • •

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GC.stat > GC.stat => { :count=>62, :heap_allocated_pages=>1416, :heap_available_slots=>577147, :heap_live_slots=>567649, :heap_free_slots=>9498, :total_allocated_pages=>1416, :total_allocated_objects=>2165898, … }

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ObjectSpace > ObjectSpace.count_objects => { :TOTAL=>577147, :FREE=>9441, :T_OBJECT=>43380, :T_CLASS=>10129, :T_MODULE=>1542, :T_FLOAT=>9, :T_STRING=>272473, … }

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ObjectSpace require "objspace" > ObjectSpace.memsize_of("Saturn V") => 40 > ObjectSpace.memsize_of(10) => 0

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rockets = [ "Saturn V", "N1", "Energia Buran", "Falcon Heavy" ] ObjectSpace.each_object(String) do |object| puts "#{object} – #{ObjectSpace.memsize_of(object)}" end => Saturn V – 40 N1 – 40 Energia Buran – 40 Falcon Heavy – 40

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memory_proﬁler require 'memory_profiler' report = MemoryProfiler.report do Rocket.find(1) end report.pretty_print => Total allocated: 692569 bytes (8457 objects) Total retained: 46495 bytes (640 objects)

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Total allocated: 692569 bytes (8457 objects) Total retained: 46495 bytes (640 objects) allocated memory by class ----------------------------------- 632937 String 37656 Array 8424 File 6624 Hash … allocated objects by class ----------------------------------- 7468 String 899 Array 23 Hash 16 Symbol …

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get_process_mem require 'get_process_mem' memory = GetProcessMem.new memory.bytes #=> 138735616 memory.kb #=> 135488.0 memory.mb #=> 132.37891 memory.gb #=> 0.1293449

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derailed_benchmarks $ bundle exec derailed bundle:mem TOP: 61.5313 MiB rails/all: 25.332 MiB rails: 11.7891 MiB slim: 1.6992 MiB slim/engine: 0.6016 MiB slim/parser: 0.3086 MiB dry-struct: 1.0508 MiB dry/struct: 1.0508 MiB

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derailed_benchmarks $ bundle exec derailed bundle:objects Total allocated: 36578388 bytes (337639 objects) Total retained: 4555830 bytes (37728 objects) allocated memory by gem ----------------------------------- 28982982 activesupport-5.1.6.1 1030516 forwardable 980919 graphql-1.7.7

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What to do next?

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number_to_currency

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Total allocated: 11044 bytes (110 objects) Total retained: 0 bytes (0 objects) allocated memory by class ----------------------------------- 5864 Hash 1792 String 1760 Array 1120 MatchData 180 BigDecimal allocated objects by class ----------------------------------- 36 Array 32 String 29 Hash 4 MatchData 2 BigDecimal

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ActiveSupport::NumberHelper NumberToCurrencyConverter NumberToDelimitedConverter NumberToHumanConverter NumberToHumanSizeConverter NumberToPercentageConverter NumberToPhoneConverter NumberToRoundedConverter • • • • • • •

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NumberConverter

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# active_support/number_helper/number_converter.rb def options @options ||= format_options.merge(opts) end def format_options default_format_options.merge!(i18n_format_options) end def default_format_options options = DEFAULTS[:format].dup options.merge!(DEFAULTS[namespace][:format]) if namespace options end

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@options ||= format_options.merge(opts) # active_support/number_helper/number_converter.rb def options end def format_options default_format_options.merge!(i18n_format_options) end def default_format_options options = DEFAULTS[:format].dup options.merge!(DEFAULTS[namespace][:format]) if namespace options end

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default_format_options.merge!(i18n_format_options) # active_support/number_helper/number_converter.rb def options @options ||= format_options.merge(opts) end def format_options end def default_format_options options = DEFAULTS[:format].dup options.merge!(DEFAULTS[namespace][:format]) if namespace options end Class Objects Memory Hash 1 192 bytes

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options = DEFAULTS[:format].dup # active_support/number_helper/number_converter.rb def options @options ||= format_options.merge(opts) end def format_options default_format_options.merge!(i18n_format_options) end def default_format_options options.merge!(DEFAULTS[namespace][:format]) if namespace options end Class Objects Memory Hash 1 192 bytes

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options.merge!(DEFAULTS[namespace][:format]) if namespace # active_support/number_helper/number_converter.rb def options @options ||= format_options.merge(opts) end def format_options default_format_options.merge!(i18n_format_options) end def default_format_options options = DEFAULTS[:format].dup options end Class Objects Memory Hash 2 384 bytes

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# active_support/number_helper/number_converter.rb def i18n_format_options locale = opts[:locale] options = I18n.translate( :'number.format', locale: locale, default: {}).dup if namespace options.merge!(I18n.translate( :"number.#{namespace}.format", locale: locale, default: {})) end options end Class Objects Memory Hash 2 384 bytes

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options = I18n.translate( :'number.format', locale: locale, default: {}).dup # active_support/number_helper/number_converter.rb def i18n_format_options locale = opts[:locale] if namespace options.merge!(I18n.translate( :"number.#{namespace}.format", locale: locale, default: {})) end options end Class Objects Memory Hash 2 384 bytes

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if namespace options.merge!(I18n.translate( :"number.#{namespace}.format", locale: locale, default: {})) end # active_support/number_helper/number_converter.rb def i18n_format_options locale = opts[:locale] options = I18n.translate( :'number.format', locale: locale, default: {}).dup options end Class Objects Memory Hash 7 1344 bytes Array 7 280 bytes

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NumberToCurrencyConverter

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# active_support/number_helper/number_to_currency_converter.rb def convert number = self.number.to_s.strip format = options[:format] if number.to_f.negative? format = options[:negative_format] number = absolute_value(number) end rounded_number = NumberToRoundedConverter.convert(number, options) format.gsub("%n", rounded_number).gsub("%u", options[:unit]) end def absolute_value(number) number.respond_to?(:abs) ? number.abs : number.sub(/\A-/, "") end Class Objects Memory Hash 7 1344 bytes Array 7 280 bytes

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number = self.number.to_s.strip # active_support/number_helper/number_to_currency_converter.rb def convert format = options[:format] if number.to_f.negative? format = options[:negative_format] number = absolute_value(number) end rounded_number = NumberToRoundedConverter.convert(number, options) format.gsub("%n", rounded_number).gsub("%u", options[:unit]) end def absolute_value(number) number.respond_to?(:abs) ? number.abs : number.sub(/\A-/, "") end Class Objects Memory Hash 7 1344 bytes Array 7 280 bytes

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number = absolute_value(number) # active_support/number_helper/number_to_currency_converter.rb def convert number = self.number.to_s.strip format = options[:format] if number.to_f.negative? format = options[:negative_format] end rounded_number = NumberToRoundedConverter.convert(number, options) format.gsub("%n", rounded_number).gsub("%u", options[:unit]) end def absolute_value(number) number.respond_to?(:abs) ? number.abs : number.sub(/\A-/, "") end Class Objects Memory Hash 7 1344 bytes Array 7 280 bytes String 2 80 bytes

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number = absolute_value(number) def absolute_value(number) number.respond_to?(:abs) ? number.abs : number.sub(/\A-/, "") end # active_support/number_helper/number_to_currency_converter.rb def convert number = self.number.to_s.strip format = options[:format] if number.to_f.negative? format = options[:negative_format] end rounded_number = NumberToRoundedConverter.convert(number, options) format.gsub("%n", rounded_number).gsub("%u", options[:unit]) end Class Objects Memory Hash 7 1344 bytes Array 7 280 bytes String 2 80 bytes

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format.gsub("%n", rounded_number).gsub("%u", options[:unit]) # active_support/number_helper/number_to_currency_converter.rb def convert number = self.number.to_s.strip format = options[:format] if number.to_f.negative? format = options[:negative_format] number = absolute_value(number) end rounded_number = NumberToRoundedConverter.convert(number, options) end def absolute_value(number) number.respond_to?(:abs) ? number.abs : number.sub(/\A-/, "") end Class Objects Memory Hash 7 1344 bytes Array 7 280 bytes String 4 160 bytes

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rounded_number = NumberToRoundedConverter.convert(number, options) # active_support/number_helper/number_to_currency_converter.rb def convert number = self.number.to_s.strip format = options[:format] if number.to_f.negative? format = options[:negative_format] number = absolute_value(number) end format.gsub("%n", rounded_number).gsub("%u", options[:unit]) end def absolute_value(number) number.respond_to?(:abs) ? number.abs : number.sub(/\A-/, "") end Class Objects Memory Hash 7 1344 bytes Array 7 280 bytes String 10 400 bytes

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NumberToRoundedConverter

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# active_support/number_helper/number_to_rounded_converter.rb def convert helper = RoundingHelper.new(options) rounded_number = helper.round(number) if precision = options[:precision] if options[:significant] && precision > 0 digits = helper.digit_count(rounded_number) precision -= digits precision = 0 if precision < 0 # don't let it be negative end … Class Objects Memory Hash 7 1344 bytes Array 7 280 bytes String 10 400 bytes

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helper = RoundingHelper.new(options) # active_support/number_helper/number_to_rounded_converter.rb def convert rounded_number = helper.round(number) if precision = options[:precision] if options[:significant] && precision > 0 digits = helper.digit_count(rounded_number) precision -= digits precision = 0 if precision < 0 # don't let it be negative end … Class Objects Memory Hash 14 2688 bytes Array 14 560 bytes String 10 400 bytes

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rounded_number = helper.round(number) # active_support/number_helper/number_to_rounded_converter.rb def convert helper = RoundingHelper.new(options) if precision = options[:precision] if options[:significant] && precision > 0 digits = helper.digit_count(rounded_number) precision -= digits precision = 0 if precision < 0 # don't let it be negative end … Class Objects Memory Hash 14 2688 bytes Array 14 560 bytes String 10 400 bytes RoundingHelper 1 40 bytes

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if precision = options[:precision] if options[:significant] && precision > 0 digits = helper.digit_count(rounded_number) precision -= digits precision = 0 if precision < 0 # don't let it be negative end # active_support/number_helper/number_to_rounded_converter.rb def convert helper = RoundingHelper.new(options) rounded_number = helper.round(number) … Class Objects Memory Hash 14 2688 bytes Array 14 560 bytes String 10 400 bytes RoundingHelper 1 40 bytes BigDecimal 2 176 bytes

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# active_support/number_helper/number_to_rounded_converter.rb … formatted_string = if BigDecimal === rounded_number && rounded_number.finite? s = rounded_number.to_s("F") s << "0" * precision a, b = s.split(".", 2) a << "." a << b[0, precision] else "%00.#{precision}f" % rounded_number end else formatted_string = rounded_number end number = NumberToDelimitedConverter.convert(formatted_string, options) format_number(number) end Class Objects Memory Hash 14 2688 bytes Array 14 560 bytes String 10 400 bytes RoundingHelper 1 40 bytes BigDecimal 2 176 bytes

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s = rounded_number.to_s("F") s << "0" * precision a, b = s.split(".", 2) a << "." a << b[0, precision] # active_support/number_helper/number_to_rounded_converter.rb … formatted_string = if BigDecimal === rounded_number && rounded_number.finite? else "%00.#{precision}f" % rounded_number end else formatted_string = rounded_number end number = NumberToDelimitedConverter.convert(formatted_string, options) format_number(number) end Class Objects Memory Hash 14 2688 bytes Array 14 560 bytes String 10 400 bytes RoundingHelper 1 40 bytes BigDecimal 2 176 bytes

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s = rounded_number.to_s("F") s << "0" * precision a, b = s.split(".", 2) a << "." a << b[0, precision] # active_support/number_helper/number_to_rounded_converter.rb … formatted_string = if BigDecimal === rounded_number && rounded_number.finite? else "%00.#{precision}f" % rounded_number end else formatted_string = rounded_number end number = NumberToDelimitedConverter.convert(formatted_string, options) format_number(number) end Class Objects Memory Hash 14 2688 bytes Array 15 (+1) 600 bytes (+40) String 15 (+5) 600 bytes (+200) RoundingHelper 1 40 bytes BigDecimal 2 176 bytes

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number = NumberToDelimitedConverter.convert(formatted_string, options) # active_support/number_helper/number_to_rounded_converter.rb … formatted_string = if BigDecimal === rounded_number && rounded_number.finite? s = rounded_number.to_s("F") s << "0" * precision a, b = s.split(".", 2) a << "." a << b[0, precision] else "%00.#{precision}f" % rounded_number end else formatted_string = rounded_number end format_number(number) end Class Objects Memory Hash 14 2688 bytes Array 15 600 bytes String 15 600 bytes RoundingHelper 1 40 bytes BigDecimal 2 176 bytes

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NumberToDelimitedConverter

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# active_support/number_helper/number_to_delimited_converter.rb def convert parts.join(options[:separator]) end private def parts left, right = number.to_s.split(".") left.gsub!(delimiter_pattern) do |digit_to_delimit| "#{digit_to_delimit}#{options[:delimiter]}" end [left, right].compact end Class Objects Memory Hash 14 2688 bytes Array 15 600 bytes String 15 600 bytes RoundingHelper 1 40 bytes BigDecimal 2 176 bytes

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# active_support/number_helper/number_to_delimited_converter.rb def convert parts.join(options[:separator]) end private def parts left, right = number.to_s.split(".") left.gsub!(delimiter_pattern) do |digit_to_delimit| "#{digit_to_delimit}#{options[:delimiter]}" end [left, right].compact end Class Objects Memory Hash 21 (+7) 4032 bytes (+1344) Array 22 (+7) 880 bytes (+280) String 15 600 bytes RoundingHelper 1 40 bytes BigDecimal 2 176 bytes

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parts.join(options[:separator]) # active_support/number_helper/number_to_delimited_converter.rb def convert end private def parts left, right = number.to_s.split(".") left.gsub!(delimiter_pattern) do |digit_to_delimit| "#{digit_to_delimit}#{options[:delimiter]}" end [left, right].compact end Class Objects Memory Hash 21 4032 bytes Array 22 880 bytes String 15 600 bytes RoundingHelper 1 40 bytes BigDecimal 2 176 bytes

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left, right = number.to_s.split(".") # active_support/number_helper/number_to_delimited_converter.rb def convert parts.join(options[:separator]) end private def parts left.gsub!(delimiter_pattern) do |digit_to_delimit| "#{digit_to_delimit}#{options[:delimiter]}" end [left, right].compact end Class Objects Memory Hash 21 4032 bytes Array 22 880 bytes String 15 600 bytes RoundingHelper 1 40 bytes BigDecimal 2 176 bytes

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left, right = number.to_s.split(".") # active_support/number_helper/number_to_delimited_converter.rb def convert parts.join(options[:separator]) end private def parts left.gsub!(delimiter_pattern) do |digit_to_delimit| "#{digit_to_delimit}#{options[:delimiter]}" end [left, right].compact end Class Objects Memory Hash 21 4032 bytes Array 23 (+1) 920 bytes (+40) String 17 (+2) 680 bytes (+80) RoundingHelper 1 40 bytes BigDecimal 2 176 bytes

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left.gsub!(delimiter_pattern) do |digit_to_delimit| "#{digit_to_delimit}#{options[:delimiter]}" end # active_support/number_helper/number_to_delimited_converter.rb def convert parts.join(options[:separator]) end private def parts left, right = number.to_s.split(".") [left, right].compact end Class Objects Memory Hash 21 4032 bytes Array 23 920 bytes String 22 880 bytes RoundingHelper 1 40 bytes BigDecimal 2 176 bytes

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left.gsub!(delimiter_pattern) do |digit_to_delimit| "#{digit_to_delimit}#{options[:delimiter]}" end # active_support/number_helper/number_to_delimited_converter.rb def convert parts.join(options[:separator]) end private def parts left, right = number.to_s.split(".") [left, right].compact end Class Objects Memory Hash 21 4032 bytes Array 23 920 bytes String 30 (+8) 1200 bytes (+320) RoundingHelper 1 40 bytes BigDecimal 2 176 bytes MatchData 2 560 bytes

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[left, right].compact # active_support/number_helper/number_to_delimited_converter.rb def convert parts.join(options[:separator]) end private def parts left, right = number.to_s.split(".") left.gsub!(delimiter_pattern) do |digit_to_delimit| "#{digit_to_delimit}#{options[:delimiter]}" end end Class Objects Memory Hash 21 4032 bytes Array 23 920 bytes String 30 1200 bytes RoundingHelper 1 40 bytes BigDecimal 2 176 bytes MatchData 2 560 bytes

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[left, right].compact # active_support/number_helper/number_to_delimited_converter.rb def convert parts.join(options[:separator]) end private def parts left, right = number.to_s.split(".") left.gsub!(delimiter_pattern) do |digit_to_delimit| "#{digit_to_delimit}#{options[:delimiter]}" end end Class Objects Memory Hash 21 4032 bytes Array 25 (+2) 1000 bytes (+80) String 30 1200 bytes RoundingHelper 1 40 bytes BigDecimal 2 176 bytes MatchData 2 560 bytes

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parts.join(options[:separator]) # active_support/number_helper/number_to_delimited_converter.rb def convert end private def parts left, right = number.to_s.split(".") left.gsub!(delimiter_pattern) do |digit_to_delimit| "#{digit_to_delimit}#{options[:delimiter]}" end [left, right].compact end Class Objects Memory Hash 21 4032 bytes Array 25 1000 bytes String 30 1200 bytes RoundingHelper 1 40 bytes BigDecimal 2 176 bytes MatchData 2 560 bytes

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parts.join(options[:separator]) # active_support/number_helper/number_to_delimited_converter.rb def convert end private def parts left, right = number.to_s.split(".") left.gsub!(delimiter_pattern) do |digit_to_delimit| "#{digit_to_delimit}#{options[:delimiter]}" end [left, right].compact end Class Objects Memory Hash 21 4032 bytes Array 25 1000 bytes String 31 (+1) 1240 bytes (+40) RoundingHelper 1 40 bytes BigDecimal 2 176 bytes MatchData 2 560 bytes

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Class Objects Memory Hash 21 4032 bytes Array 25 1000 bytes String 31 1240 bytes RoundingHelper 1 40 bytes BigDecimal 2 176 bytes MatchData 2 560 bytes Total 82 7048 bytes

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Class Objects Memory Hash 21 4032 bytes Array 25 1000 bytes String 31 1240 bytes RoundingHelper 1 40 bytes BigDecimal 2 176 bytes MatchData 2 560 bytes Total 82 7048 bytes

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Lets make number_to_currency great again!

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How to make number_to_currency great again?

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What we learned

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What we learned Do not repeat yourself; •

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What we learned Do not repeat yourself; Do not create objects that you do not need; • •

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What we learned Do not repeat yourself; Do not create objects that you do not need; Use bang methods to modify an object instead of creating a new one; • • •

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What we learned Do not repeat yourself; Do not create objects that you do not need; Use bang methods to modify an object instead of creating a new one; Use methods like insert to modify a string instead of creating a new one; • • • •

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97532.5734 → $ 97,532.57

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97532.5734 → $ 97,532.57 def number_to_currency(number, options)

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97532.5734 → $ 97,532.57 def number_to_currency(number, options)

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97532.5734 → $ 97,532.57 def number_to_currency(number, options) string = number_to_string(number, options)

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97532.5734 → $ 97,532.57 def number_to_currency(number, options) string = number_to_string(number, options) add_delimiters(string, number, options)

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97532.5734 → $ 97,532.57 def number_to_currency(number, options) string = number_to_string(number, options) add_delimiters(string, number, options) add_unit(string, number, options)

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97532.5734 → $ 97,532.57 def number_to_currency(number, options) string = number_to_string(number, options) add_delimiters(string, number, options) add_unit(string, number, options) string end

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97532.5734 → 97532.57 def number_to_string(number, options)

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97532.5734 → 97532.57 def number_to_string(number, options)

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97532.5734 → 97532.57 def number_to_string(number, options) string = number.round( options[:precision]).to_s end

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97532.5734 → 97532.57 def number_to_string(number, options) string = number.round( options[:precision]).to_s end

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97532.5734 → 97532.57 def number_to_string(number, options) string = number.round( options[:precision]).to_s end

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97532.5734 → 97532.57 def number_to_string(number, options) string = number.round( options[:precision]).to_s end

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97532.5734 → 97532.57 def number_to_string(number, options) string = number.round( options[:precision]).to_s

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97532.5734 → 97532.57 def number_to_string(number, options) string = number.round( options[:precision]).to_s

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97532.5734 → 97532.57 def number_to_string(number, options) string = number.round( options[:precision]).to_s dot_index = string.rindex(".")

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97532.5734 → 97532.57 def number_to_string(number, options) string = number.round( options[:precision]).to_s dot_index = string.rindex(".")

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97532.5734 → 97532.57 def number_to_string(number, options) string = number.round( options[:precision]).to_s dot_index = string.rindex(".") fractional = string.size - dot_index - 1

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97532.5734 → 97532.57 def number_to_string(number, options) string = number.round( options[:precision]).to_s dot_index = string.rindex(".") fractional = string.size - dot_index - 1

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97532.5734 → 97532.57 def number_to_string(number, options) string = number.round( options[:precision]).to_s dot_index = string.rindex(".") fractional = string.size - dot_index - 1 zeros_to_add = options[:precision] - fractional

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