SLOMO - Speaker Deck

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slomo the movie www. .com Special thanks

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Introducing Dr. John Kitchin The neurologist

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Introducing Dr. John Kitchin The inspiration

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Introducing Dr. John Kitchin The skater

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What is your goal in life?

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Grow up

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Pick a career

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Buy a sports car

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Retire

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The faster the better

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Slomo

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Said “no”

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Introducing Schneems The narrator

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Sounds like “schnapps”

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The narrator said, explaining his own introduction

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Maintain Sprockets

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Those are all my hobbies

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Full time job:

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Resisting the Trump Administration

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I consider myself a very chill person

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Like to mix my yoga habits with resistance

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“ohm”

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BTW

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In this talk we will not use “nil”

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Naan

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Sorry for ny naan jokes

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Sorry for ny naan jokes

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This

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talk

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about

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speed

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The fastest way to get where you’re going

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Depends on where you’re going

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To get there faster

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Let’s slow down

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Why would we want slower code?

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Measure it

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task "assets:profile" do puts "==============" StackProf.run(mode: :wall, out: "tmp/stackprof.dump") do Rake::Task["assets:precompile"].invoke end puts "Running: $ stackprof tmp/stackprof.dump" puts `stackprof tmp/stackprof.dump` end

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$ stackprof tmp/stackprof.dump

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Running: $ stackprof tmp/stackprof.dump ================================== Mode: wall(1000) Samples: 2083 (62.23% miss rate) GC: 282 (13.54%) ================================== TOTAL (pct) SAMPLES (pct) FRAME 313 (15.0%) 313 (15.0%) Set#include? 307 (14.7%) 243 (11.7%) Sprockets::DigestUtils#digest 743 (35.7%) 137 (6.6%) Kernel#require 476 (22.9%) 124 (6.0%) Kernel#require 157 (7.5%) 92 (4.4%) SassC::Rails::Importer#imports 243 (11.7%) 81 (3.9%) # 67 (3.2%) 67 (3.2%) NumericWithFormat#to_s 160 (7.7%) 53 (2.5%) PathUtils#atomic_write 44 (2.1%) 44 (2.1%) # 239 (11.5%) 37 (1.8%) Sprockets::Cache::FileStore#set

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26% of total execution samples

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What is calling so much? Set#include?

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$ stackprof tmp/stackprof.dump --method Set#include? Set#include? (/Users/richardschneeman/.rubies/ruby-2.3.1/lib/ruby/2.3.0/set.rb:214) samples: 313 self (15.0%) / 313 total (15.0%) callers: 312 ( 99.7%) Sprockets::ProcessorUtils#valid_processor_metadata_value? 1 ( 0.3%) Sprockets::Utils#dfs_paths code: | 214 | def include?(o) 313 (15.0%) / 313 (15.0%) | 215 | @hash[o] | 216 | end

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What is calling so much? valid_processor_metadata_value?

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$ stackprof tmp/stackprof.dump --method Sprockets::ProcessorUtils#valid_processor_metadata_value? Sprockets::ProcessorUtils#valid_processor_metadata_value? (/Users/richardschneeman/.gem/ruby/2.3.1/bundler/ gems/sprockets-3b0d6732c13f/lib/sprockets/processor_utils.rb:170) samples: 24 self (1.2%) / 2129 total (102.2%) callers: 1793 ( 84.2%) Sprockets::ProcessorUtils#valid_processor_metadata_value? 336 ( 15.8%) Sprockets::ProcessorUtils#validate_processor_result! callees (2105 total): 1793 ( 85.2%) Sprockets::ProcessorUtils#valid_processor_metadata_value? 312 ( 14.8%) Set#include? code: | 170 | def valid_processor_metadata_value?(value) 261 (12.5%) / 2 (0.1%) | 171 | if VALID_METADATA_VALUE_TYPES.include?(value.class) | 172 | true 61 (2.9%) / 8 (0.4%) | 173 | elsif VALID_METADATA_COMPOUND_TYPES.include?(value.class) 1806 (86.7%) / 13 (0.6%) | 174 | value.all? { |v| valid_processor_metadata_value?(v) } | 175 | else 1 (0.0%) / 1 (0.0%) | 176 | false | 177 | end

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def valid_processor_metadata_value?(value) if VALID_METADATA_VALUE_TYPES.include?(value.class) true elsif VALID_METADATA_COMPOUND_TYPES.include?(value.class) value.all? { |v| valid_processor_metadata_value?(v) } else false end end

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Set#include?

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# File set.rb, line 214 def include?(o) @hash[o] end

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Set is powered by a Hash under the hood

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Skip the Set, just use a Hash

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But why?

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Ruby has optimized instructions for hash calls

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code = " foo = Hash.new foo[:bar] " puts RubyVM::InstructionSequence.compile(code).disasm # 0000 trace 1 ( 2) # 0002 getinlinecache 9, # 0005 getconstant :Hash # 0007 setinlinecache # 0009 opt_send_without_block , # 0012 setlocal_OP__WC__0 2 # 0014 trace 1 ( 3) # 0016 getlocal_OP__WC__0 2 # 0018 putobject :bar # 0020 opt_aref , # 0023 leave

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Compare to Set

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code = " s = Set.new s.include?(:bar) " puts RubyVM::InstructionSequence.compile(code).disasm # 0000 trace 1 ( 2) # 0002 getinlinecache 9, # 0005 getconstant :Set # 0007 setinlinecache # 0009 opt_send_without_block , # 0012 setlocal_OP__WC__0 2 # 0014 trace 1 ( 3) # 0016 getlocal_OP__WC__0 2 # 0018 putobject :bar # 0020 opt_send_without_block , # 0023 leave

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insns.def

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/** @c optimize @e [] @j 最適化された recv[obj]。 */ DEFINE_INSN opt_aref (CALL_INFO ci, CALL_CACHE cc) (VALUE recv, VALUE obj) (VALUE val) { if (!SPECIAL_CONST_P(recv)) { if (RBASIC_CLASS(recv) == rb_cArray && BASIC_OP_UNREDEFINED_P(BOP_AREF, ARRAY_REDEFINED_OP_FLAG) && FIXNUM_P(obj)) { val = rb_ary_entry(recv, FIX2LONG(obj)); } else if (RBASIC_CLASS(recv) == rb_cHash && BASIC_OP_UNREDEFINED_P(BOP_AREF, HASH_REDEFINED_OP_FLAG)) { val = rb_hash_aref(recv, obj); } else { goto INSN_LABEL(normal_dispatch); } } else { INSN_LABEL(normal_dispatch): PUSH(recv); PUSH(obj); CALL_SIMPLE_METHOD(recv); } }

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Versus

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/** @c optimize @e Invoke method without block @j Invoke method without block */ DEFINE_INSN opt_send_without_block (CALL_INFO ci, CALL_CACHE cc) (...) (VALUE val) // inc += -ci->orig_argc; { struct rb_calling_info calling; calling.blockptr = NULL; vm_search_method(ci, cc, calling.recv = TOPN(calling.argc = ci->orig_argc)); CALL_METHOD(&calling, ci, cc); }

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Ruby optimizes Hash calls by Skipping Method Lookup

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BTW

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Don’t subclass Hash

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  “I don’t subclass hash”

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Hash With Indifferent Access

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Hashie

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Rack:: Utils::  HeaderHash

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Rack is 23% faster without HeaderHash

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Don’t subclass Hash

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Switch Set to a hash

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VALID_METADATA_VALUE_TYPES_HASH = VALID_METADATA_VALUE_TYPES. each_with_object({}) do |type, hash| hash[type] = true end.freeze def valid_processor_metadata_value?(value) if VALID_METADATA_VALUE_TYPES_HASH[value.class] true elsif VALID_METADATA_COMPOUND_TYPES_HASH[value.class] value.all? { |v| valid_processor_metadata_value?(v) } else false end end

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Skips Method Lookup

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Did it help?

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18.325s 17.981s

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1.8% Faster!

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Bugger

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Keep gliding

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Round 2

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TOTAL (pct) SAMPLES (pct) FRAME 2328 (109.6%) 362 (17.0%) Sprockets::ProcessorUtils# valid_processor_metadata_value? 348 (16.4%) 256 (12.1%) Sprockets::DigestUtils#digest 486 (22.9%) 106 (5.0%) Kernel#require 97 (4.6%) 97 (4.6%) ActiveSupport:: NumericWithFormat#to_s 123 (5.8%) 94 (4.4%) Sprockets::PathUtils#atomic_write 581 (27.4%) 76 (3.6%) Kernel#require 61 (2.9%) 61 (2.9%) # .mechanism 193 (9.1%) 52 (2.4%) Sprockets::Cache::FileStore#set 95 (4.5%) 48 (2.3%) SassC::Rails::Importer# imports 36 (1.7%) 36 (1.7%) ExecJS::ExternalRuntime# exec_runtime 59 (2.8%) 25 (1.2%) Kernel#require 75 (3.5%) 25 (1.2%) Module#delegate

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$ stackprof tmp/stackprof.dump --method Sprockets::DigestUtils#digest # . . . Sprockets::DigestUtils#digest (lib/sprockets/digest_utils.rb:46) samples: 4 self (0.2%) / 7 total (0.3%) callers: 5 ( 71.4%) Sprockets::Cache#expand_key 2 ( 28.6%) Sprockets::Loader#load_from_unloaded callees (3 total): 3 ( 100.0%) Sprockets::DigestUtils#digest_class code: | 46 | def digest(obj) 4 (0.2%) / 1 (0.0%) | 47 | digest = digest_class.new | 48 | queue = [obj] | 49 | | 50 | while queue.length > 0 | 51 | obj = queue.shift | 52 | klass = obj.class | 53 | 2 (0.1%) / 2 (0.1%) | 54 | if klass == String | 55 | digest << obj | 56 | elsif klass == Symbol | 57 | digest << 'Symbol' | 58 | digest << obj.to_s | 59 | elsif klass == Fixnum

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Let me paraphrase

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if String

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if String elsif Symbol

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if String elsif Symbol elsif Fixnum

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if String elsif Symbol elsif Fixnum elsif Bignum

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if String elsif Symbol elsif Fixnum elsif Bignum elsif TrueClass

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if String elsif Symbol elsif Fixnum elsif Bignum elsif TrueClass elsif FalseClass

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if String elsif Symbol elsif Fixnum elsif Bignum elsif TrueClass elsif FalseClass elsif NilClass

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if String elsif Symbol elsif Fixnum elsif Bignum elsif TrueClass elsif FalseClass elsif NilClass elsif Array

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if String elsif Symbol elsif Fixnum elsif Bignum elsif TrueClass elsif FalseClass elsif NilClass elsif Array elsif Hash

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if String elsif Symbol elsif Fixnum elsif Bignum elsif TrueClass elsif FalseClass elsif NilClass elsif Array elsif Hash elsif Set

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if String elsif Symbol elsif Fixnum elsif Bignum elsif TrueClass elsif FalseClass elsif NilClass elsif Array elsif Hash elsif Set elsif Encoding

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If we pass in a Set object, we must make 10 comparisons

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if String elsif Symbol elsif Fixnum elsif Bignum elsif TrueClass elsif FalseClass elsif NilClass elsif Array elsif Hash elsif Set elsif Encoding Expand and Iterate

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if/elsif is hidden iteration

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How do we go faster?

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Get rid of iteration

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Case statements

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Hash loOkups

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Before

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def digest(obj) digest = digest_class.new queue = [obj] while queue.length > 0 obj = queue.shift klass = obj.class if klass == String digest << obj elsif klass == Symbol digest << 'Symbol' digest << obj.to_s elsif klass == Fixnum digest << 'Fixnum' digest << obj.to_s elsif klass == Bignum digest << 'Bignum' digest << obj.to_s elsif klass == TrueClass digest << 'TrueClass' elsif klass == FalseClass digest << 'FalseClass' elsif klass == NilClass digest << 'NilClass'.freeze elsif klass == Array digest << 'Array' queue.concat(obj) elsif klass == Hash digest << 'Hash' queue.concat(obj.sort) elsif klass == Set digest << 'Set' queue.concat(obj.to_a) elsif klass == Encoding digest << 'Encoding' digest << obj.name else raise TypeError, "couldn't digest #{klass}" end end digest.digest end

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After

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def digest(obj) digest = digest_class.new ADD_VALUE_TO_DIGEST[obj.class].call(obj, digest) digest.digest end

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Store logic in a Hash

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def digest(obj) digest = digest_class.new ADD_VALUE_TO_DIGEST[obj.class].call(obj, digest) digest.digest end Constant time lookup

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Logic Lives in Lambdas

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ADD_VALUE_TO_DIGEST = { String => ->(val, digest) { digest << val }, FalseClass => ->(val, digest) { digest << 'FalseClass'.freeze }, TrueClass => ->(val, digest) { digest << 'TrueClass'.freeze }, NilClass => ->(val, digest) { digest << 'NilClass'.freeze }, Symbol => ->(val, digest) { digest << 'Symbol'.freeze digest << val.to_s }, Integer => ->(val, digest) { digest << 'Integer'.freeze digest << val.to_s }, Array => ->(val, digest) { digest << 'Array'.freeze val.each do |element| ADD_VALUE_TO_DIGEST[element.class].call(element, digest) end },

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zOMG WAT

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Recursive hash is Recursive

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Faster?

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14.9s 12.54s

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16% faster asset compilation with no cache

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Repeat for all supported types

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Who likes audience participation?

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Can we go faster?

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ADD_VALUE_TO_DIGEST[String] ADD_VALUE_TO_DIGEST[Hash] ADD_VALUE_TO_DIGEST[true] ADD_VALUE_TO_DIGEST[false] ADD_VALUE_TO_DIGEST[nil] ADD_VALUE_TO_DIGEST[Array] ADD_VALUE_TO_DIGEST[Set] ADD_VALUE_TO_DIGEST[Integer]

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String Hash true false nil Array Set Integer All Constants

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Hash# compare_by_identity

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Compare object, not value

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String Hash true false nil Array Set Integer All Constants

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7% speed improvement

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Let’s slow it down

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What did we do?

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Identify a goal

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Gather potentially useful tools

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Iterate on the problem

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RubyVM::InstructionSequence.compile(code).disasm

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Shoulders of giants

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The more you understand about _how_ your code works, the faster you can make it

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Find a speed buddy

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(or buddies)

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“C” how fast your program will go

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gem 'sassc-rails'

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Sassc uses libsass

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31% faster

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Sprockets 4 will support sassc out of the box (but not yet)

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Don’t abandon your language for speed

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Find the slow parts and tag team them with other languages

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C-extensions

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Use Rust with helix

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Use Go with gorb

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p.s. have you tried JRuby?

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What about cached compile times

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Bootscale caches require lookups

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Without it, the more gems on your system the LONGER `require` takes

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6s cached compile times 2s cached compile times

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300% faster

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Don’t be an asshole

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Don’t appologize for the programing language you love

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Set your own goals

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Go at your own speed

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These are the good days of our programming life

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Live them to the fullest

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