Micro-optimizing Ruby

A talk originally given to the Dallas Ruby Brigade and then re-presented as an online lunch and learn.

https://www.youtube.com/watch?v=3HpjZPbBS-s

Transcript

1. M icro-optim izing Ruby For big wins!
2. You shouldn’t do it. Um, what? I guess we’re done.
3. Bigger Optimizations • SQL queries • n + 1 queries • Ruby version • server software • server configuration • caching • sharding Smarter Co-workers
4. You should do it.
5. You’ll learn more about Ruby. 1
6. Technically Faster The best kind of faster. 2
7. Small changes can add up. 3
8. Richard Schneems
10. -37,452
12. .freeze
13. 5.times do 'hell' end
14. 5.times do 'hell'.freeze end
15. a few caveats
16. pry> 2.frozen? => true pry> :hi.frozen? => true
17. pry> 10.times { 'hello' } Total allocated: 400 bytes (10 objects) pry> h = {} pry> 10.times { h['hello'] } Total allocated: 40 bytes (1 objects)
18. pry> ['hello', 'world'].freeze => ["hello", "world"] pry> _.first.frozen? => false
19. name = 'world'.freeze "hello #{name}".freeze
21. pry> word = 'hello' => "hello" pry> word.gsub('h', 'c') => "cello" pry> word => "hello"
22. pry> word = 'hello' => "hello" pry> word.gsub!('h', 'c') => "cello" pry> word => "cello"
23. a caveat
24. pry> word.gsub('a', 'b') => "hello" pry> word.gsub!('a', 'b') => nil
25. pry> [2, 4, 6].select!(&:even?) => nil pry> [2, 4, 6].keep_if(&:even?) => [2, 4, 6] pry> [2, 4, 6].reject!(&:odd?) => nil pry> [2, 4, 6].delete_if(&:odd?) => [2, 4, 6]
26. optim ized m ethods
27. We can make it better! keys.each map {}.flatten reverse.each each.with_index each.with_object
28. We can make it better! keys.each map {}.flatten reverse.each each.with_index each.with_object each_key reverse_each each_with_object each_with_index flat_map {}
29. If you see two existing methods joined with an underscore. It’s probably an optimization.
30. colors .reverse .each do |color| puts color end
31. colors .reverse .each do |color| puts color end
32. colors .reverse_each do |c| puts c end
33. colors .reverse .each colors .reverse_each
34. a caveat
35. colors .reverse .each colors .reverse_each
36. som e things you just have to know
39. Calculating ------------------------------------- String#=~ 56.672k i/100ms String#start_with? 118.308k i/100ms ------------------------------------------------- String#=~ 919.574k (± 6.4%) i/s - 4.590M String#start_with? 4.177M (± 6.4%) i/s - 20.822M Comparison: String#start_with?: 4177162.6 i/s String#=~: 919574.2 i/s - 4.54x slower
40. benchmark-ips
41. require 'benchmark/ips' Benchmark.ips do |x| x.report('fast code') do fast end x.report('slow code') do slow end x.compare! end
42. Calculating ------------------------------------- fast 85.749k i/100ms slow 35.529k i/100ms ------------------------------------------------- fast 1.867M (± 7.6%) i/s - 9.347M slow 467.095k (± 6.4%) i/s - 2.345M Comparison: fast: 1866669.5 i/s slow: 467095.4 i/s - 4.00x slower
43. memory_profiler
44. require 'memory_profiler' MemoryProfiler.report do code.to.run end.pretty_print
49. questions?