Making Rails Not Slow

Presented at Ruby Meetup Ljubljana on 28. Jan 2016

Transcript

1. MAKING RAILS FAST DANE ŠOBA DANE.SOBA@GMAIL.COM
2. MAKING RAILS NOT SLOW DANE ŠOBA DANE.SOBA@GMAIL.COM
3. WHY PERFORMANCE MATTERS?
4. TIME = MONEY
5. MAKING RAILS NOT SLOW WHY PERFORMANCE MATTERS? ▸ customer experience ▸ hosting costs ▸ SEO ranking ▸ developer experience
6. TIME = SALES
7. HALF A SECOND DELAY CAUSED A 20% DROP IN TRAFFIC. Google research, 2004 MAKING RAILS NOT SLOW
8. EVERY 100 MS OF LATENCY COST 1% IN SALES Amazon research, 2008 MAKING RAILS NOT SLOW
9. MAKING RAILS NOT SLOW RESPONSE TIME USER PERCEPTION <100ms Instant 200ms Fast 300ms Ok 500ms Sluggish 1s Frustrating 2s RAAGEEE
10. TIME = COST
11. MAKING RAILS NOT SLOW RESPONSE TIME REQUESTS / SECOND 100ms 10 200ms 5 300ms 3 500ms 2 700ms 1 1s 1
12. MAKING RAILS NOT SLOW RESPONSE TIME REQUESTS / INSTANCE (2 PROCESS) 100ms 20 200ms 10 300ms 7 500ms 4 700ms 3 1s 2
13. MAKING RAILS NOT SLOW RESPONSE TIME INSTANCES FOR 1000 RPM 100ms 1 200ms 2 300ms 3 500ms 4 700ms 6 1s 8
14. MAKING RAILS NOT SLOW RESPONSE TIME HEROKU COST 100ms $25 200ms $50 300ms $75 500ms $125 700ms $175 1s $225
15. WHY IS RUBY SLOW?
16. MAKING RAILS NOT SLOW WHY IS RUBY SLOW? ▸ Single threaded / GIL ▸ Blocking ▸ Interpreted ▸ Very dynamic ▸ Garbage collected
17. MAKING RAILS NOT SLOW SINGLE THREADED Request 1 Request 2 Request 3
18. MAKING RAILS NOT SLOW BLOCKING Request Database API File
19. MAKING RAILS NOT SLOW DOING NOTHING Request Database API File
20. MAKING RAILS NOT SLOW DYNAMIC & INTERPRETED ▸Interpreting is slow ▸Dynamic code is hard to optimize ▸Improved in recent ruby versions
21. MAKING RAILS NOT SLOW GARBAGE COLLECTION Request GC GC Random GC pauses
22. HOW TO OPTIMIZE?
23. PREMATURE OPTIMIZATION IS THE ROOT OF ALL EVIL Donald Knuth MAKING RAILS NOT SLOW
24. MEASURE THEN OPTIMIZE
25. MAKING RAILS NOT SLOW MEASURING PERFORMANCE ▸ rails timing logs ▸ benchmark helper ▸ ab - apache benchmark ▸ heroku database metrics ▸ new relic monitoring ▸ slow query logs
26. MAKING RAILS NOT SLOW RAILS LOG TIMINGS
27. MAKING RAILS NOT SLOW BENCHMARK HELPER <% benchmark "Process data files" do %> <%= expensive_files_operation %> <% end %> Process data files (345.2ms)
28. MAKING RAILS NOT SLOW APACHE BENCH ab -n100 http://127.0.0.1:3000 Requests per second: 4.09 [#/sec] (mean) Time per request: 244.221 [ms] (mean) Percentage of the requests served within a certain time (ms) 50% 224 66% 231 75% 236 80% 246 90% 314 95% 388 98% 435 99% 3247 100% 3247 (longest request)
29. MAKING RAILS NOT SLOW NEW RELIC ▸ cloud performance monitoring ▸ easy setup ▸ slow transaction breakdown
30. OPTIMIZE SLOWEST FIRST
31. WHAT TO OPTIMIZE?
32. MAKING RAILS NOT SLOW UPGRADE RUBY VERSION ▸ Improved performance in ruby >2.0 ▸ rbenv for version management
33. ONE WEIRD TRICK TO MAKE ASSETS 3X FASTER IN DEVELOPMENT
34. MAKING RAILS NOT SLOW DISABLE ASSET DEBUG MODE config.assets.debug = false development.rb shortens every page load by anywhere from 300 - 1000 ms
35. MAKING RAILS NOT SLOW DISABLE ASSET DEBUG MODE DON’T I NEED THIS? config.assets.debug = true config.assets.debug = false ▸ separate file for each JS & CSS ▸ 300-1000+ ms ▸ multiple files (1:1) ▸ multiple downloads ▸ Concat JS & CSS ▸ <100ms ▸ 1 file ▸ 1 download
36. MAKING RAILS NOT SLOW AVOID N+1 QUERIES @comments = Comment.limit(20) <% @comments.each do |comment| %> <%= comment.author.name %> <% end %>
37. MAKING RAILS NOT SLOW AVOID N+1 QUERIES @comments = Comment.limit(20) <% @comments.each do |comment| %> <%= comment.author.name %> <% end %> 1 query 20 queries lazy load Check generated SQL in logs!
38. MAKING RAILS NOT SLOW AVOID N+1 QUERIES @comments = Comment.includes(:author).limit(20) <% @comments.each do |comment| %> <%= comment.author.name %> <% end %> 2 queries eager load
39. MAKING RAILS NOT SLOW ADD SQL INDEXES ▸ indexes can make a huge difference ▸ index foreign keys ▸ index full text queries ▸ index popular SQL queries ▸ don’t index everything
40. MAKING RAILS NOT SLOW AVOID EXPENSIVE SQL ▸ avoid many joins ▸ avoid outer joins ▸ use SQL aggregates instead of rails code (sum, group by, …) ▸ use Model.select for large models
41. MAKING RAILS NOT SLOW VIEW CACHING ▸ Great for popular complex views ▸ Simple to use ▸ Refresh on model updated_at
42. MAKING RAILS NOT SLOW VIEW CACHING <% cache product do %> <%= product.name %> <% end %> cache key: views/products/1-201505056193031061005000/bea67108094918eeba42cd4a6e786901
43. MAKING RAILS NOT SLOW VIEW CACHING ▸ enable in-memory caching in development ▸ memcached in production ▸ distributed memcached for cloud hosting
44. WARNING: STRONG OPINIONS AHEAD
45. MAKING RAILS NOT SLOW AVOID TURBOLINKS ▸ hard to reason about ▸ two types of page load ▸ must include scripts in head ▸ breaks third-party scripts ▸ broken back button on error ▸ clashes with interactive pages
46. MAKING RAILS NOT SLOW AVOID HAML ▸ up to 10x slower than ERB ▸ large overhead under 300ms ▸ causes random GC ▸ terrible hash syntax for attributes
47. MAKING RAILS NOT SLOW HAML ALTERNATIVES ▸ fastest ▸ default, well known ▸ designer friendly ERB SLIM ▸ as fast as ERB ▸ HAML done right ▸ can use for XML FAML / HAMLIT ▸ high-performance HAML reimplementation ▸ legacy projects?
48. MAKING RAILS NOT SLOW AVOID COFFEESCRIPT INTERPOLATION index.html.haml :javascript var data = #{@data.to_json}; :coffeescript data = #{@data.to_json}
49. MAKING RAILS NOT SLOW AVOID COFFEESCRIPT INTERPOLATION index.html.haml :javascript var data = #{@data.to_json}; :coffeescript data = #{@data.to_json} <1 ms Interpolates text 300 ms Compiles JS Each request:
50. PRODUCTION SETTINGS
51. MAKING RAILS NOT SLOW WEBRICK ▸ Not good for production traffic ▸ Single-threaded ▸ Blocked by slow clients ▸ Inefficient for serving assets
52. MAKING RAILS NOT SLOW MULTI-PROCESS ▸ run several app processes ▸ better concurrency ▸ limited by memory
53. MAKING RAILS NOT SLOW GZIP ▸ compress responses & assets ▸ up to 90% compression ▸ always enable
54. MAKING RAILS NOT SLOW ASSET CACHE HEADERS ▸ enable long-term cache headers on assets ▸ asset hash fingerprints for invalidation ▸ no headers by default in rails ▸ could use CDN for assets (e.g. Amazon Cloudfront)
55. MAKING RAILS NOT SLOW PHUSION PASSENGER ▸ NGINX or Apache server ▸ GZIP & asset caching ▸ simple setup ▸ processes shared memory ▸ out-of-band GC
56. MAKING RAILS NOT SLOW FRONTEND OPTIMIZATIONS ▸ gzip ▸ cache headers ▸ script at end of body ▸ lazy-load images ▸ YSlow, Google Page Speed
57. SUMMARY
58. MAKING RAILS NOT SLOW SUMMARY ▸ Performance matters ▸ Time = money ▸ Why is ruby slow ▸ Measure, then optimise ▸ Optimisation techniques ▸ Production settings
59. MAKE YOUR APPS NOT SLOW
60. QUESTIONS?