Rails from "good" to fast - Colognerb

Rails from "good" to fast. How to get the view rendering from ~600ms to ~60ms.
https://github.com/timoschilling/YetAnotherBlog
https://github.com/apotonick/cells
https://github.com/apotonick/representable

Transcript

1. Rails from
   “good” to fast
   How to get the view rendering
   from ~600ms to ~60ms
   

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2. What’s the slowest
   part in Rails?
   • Request Handling (ActionDispatch)
   • NO!
   • Database Queries (ActiveRecord)
   • NO, just a bit!
   • Rendering (ActionView, HAML, JBuilder)
   • YES!
   

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3. Let’s build a Blog
   github.com/timoschilling/YetAnotherBlog
   Why ~5ms?
   

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4. Asset Overhead
   Prod
   Dev
   1 Asset
   Dev
   100 Assets
   

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5. Fix Asset Overhead
   How?
   Dev
   1 Asset
   Dev
   100 Assets
   

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6. Even Faster?
   

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7. The Code
   

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8. Render a Index with
   100 Items
   

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9. Side Note:

   Every Query is a lie!
   0.3ms + 0.4ms + 4.4ms +0.6ms = 5.7ms
   5.7ms != 6.1ms
   

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11. Why 5.7ms != 6.1ms?
    ActiveRecord show only the query time!
    Not the real amount of each operation!
    

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12. How to get a real value?
    Before:
    (0.3ms) SELECT COUNT(*)…

    Post Load (0.4ms) …

    User Load (0.4ms) …

    Comment Load (4.4ms) …

    User Load (0.6ms) …
    

    

    Completed in 568ms

    (Views: 561.9ms |

    ActiveRecord: 6.1ms)
    After:
    (0.3ms) SELECT COUNT(*)…

    Post Load (0.4ms) …

    User Load (0.4ms) …

    Comment Load (4.4ms) …

    User Load (0.6ms) …

    

    DB Queries: 78.85ms

    

    Completed in 568ms

    (Views: 489,1ms |

    ActiveRecord: 6.1ms)
    

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13. Hint!
    If you use Trailblazer:

    You will get this kind of measurement
    for free, in the future.
    

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14. How to make it
    faster?
    Cache!?
    

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15. Russian Doll Caching
    from
    570ms
    to
    677ms
    ???
    

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16. Russian Doll Caching
    It helps only if you have slow views!
    This view has the same render time as a view
    without `sleep` with Russian Doll Caching
    

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17. good old
    Rails.cache.fetch
    It’s fast!

    But now I need to manage the cache!

    :(
    85ms
    

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18. tl;dr
    Rails caching sucks!
    

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19. Again:
    How to make it faster?
    Don’t use ActionView!
    But how?
    Use Cells!
    

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20. Cells?
    A gem for ViewModel’s,

    written by this awesome guy:
    

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21. Demo
    

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22. Status:

    ~650ms -> ~150ms
    

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23. Where is the Time?
    • 150ms Request
    • DB: 70ms
    • ActiveRecord: 6.1ms
    • ActionView: 78.1ms
    • Cells: 71.4ms
    

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24. Next Step:
    remove index (action)view
    (demo)
    

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25. Where is the Time?
    • 145ms Request
    • DB: 70ms
    • ActiveRecord: 6.1ms
    • ActionView: 74.1ms
    • Cells: 71.4ms
    

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26. Next Step:
    remove layout (action)view
    (demo)
    

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27. Where is the Time?
    • 145ms Request
    • DB: 70ms
    • ActiveRecord: 6.1ms
    • Cells: 71.4ms
    

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28. How does tempting
    works?
    

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29. Why need that ~70ms?
    • 1 Layout
    • Index List
    • 100 Post
    • + 1 User
    • + 1 Comment
    • + 1 User
    • = 404 Renderings
    • 404 Renderings
    • each rendering
    needs 100 method
    call (theoretical
    assumption)
    

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30. 70ms vs. 4ms
    Where the time goes by?
    Tilt!
    

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31. What does Tilt do?
    • one time
    • compile the template
    • build a method
    • cache this method
    • per rendering
    • bind the method to the context
    • call the method
    • unbind the method from context
    • one time
    • compile the template
    • build a method
    • cache this method
    • per rendering
    • bind the method to the context
    • call the method
    • unbind the method from context
    

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32. Solution:
    Hand build tilt replacement
    

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33. Where is the Time?
    • 91ms Request
    • DB: 70ms
    • ActiveRecord: 6.1ms
    • Cells: 17.4ms
    

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34. ActiveSupport::Notifications
    • Nice
    • But slow
    • One event costs ~0.05ms
    

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35. Path helpers
    • post_path(model) # => f***ing slow
    • post_path(id: model.id) # => slow
    • “/posts/#{id}” # => fast
    • brings up to 4ms (50%)
    

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36. Cell::Mailer
    

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37. Real World App
    

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38. Jbuilder
    

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39. Faster? How?
    A gem JSON/XML Object Mapper,

    written by this awesome guy:
    Representable
    

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40. Representable
    

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41. Jbuilder

    vs.

    Representable
    from ~230ms to ~80ms
    

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42. Form’s
    SimpleForm
    

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43. Faster? How?
    A form builder gem,

    written by this awesome guy:
    Formular
    

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44. Formular
    SimpleForm 11ms
    vs.
    Formular 0.6ms
    

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45. Disclamer
    I’m an apotonick fanboy!
    

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46. The End
    

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47. Tanks!
    

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48. Questions?
    

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49. Links
    • github.com/timoschilling/YetAnotherBlog
    • github.com/apotonick/cells
    • github.com/apotonick/representable
    

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