The document provides tips for scaling Rails sites by improving client-side, database, and Rails performance. Some key recommendations include using a CDN, caching assets, adding indexes to databases, avoiding N+1 queries, using efficient Ruby code, and caching partials and fragments to reduce application overhead. The overall message is to optimize for caching, minimize database and application requests, and leverage other languages or systems when Ruby or Rails APIs are slow.

1. Scaling Rails Site
by default

2. General Scaling
Scaling Rails Site :
Reading Material #1- #5
http://blog.xdite.net/?cat=91

3. •Client-side Performance
• Database Performance
• Rails Performance

4. Client-side Performance

5. 150ms > 5ms

6. YSlow!

7. Cookie Free Domain

8. main site http://www.example.org
static site http://asset.example.org

9. main site http://example.org
static site http://example-static.org

10. config.action_controller.asset_host =
“asset.example.org”

11. CDN

12. image_tag
http://asset.example.org/photos/small.jpg?1269316198

13. Parallel Download

14. config.action_controller.asset_host =
“asset%d.example.org”

15. Minimal HTTP Request

16. <%= javascript_include_tag :default, :cache => true %>
<%=stylesheet_link_tag “main”, :cache => true %>
http://asset.example.org/javascripts/all.js?1269316198
http://asset.example.org/stylesheets/all.css?1269316198

17. Cache-Control

18. def index
do_somthing
expires_in 10.minutes
end
header[“Cache-Control”] = “max-age=600”

19. ETags

21. def show
@user = User.find(params[:id])
if stale?(:etag => @user)
@content = @user.very_expensive_call
respond_to do |format|
formant.html.erb
end
end
end
304 Not Modified

22. Last Modified

23. [‘Last-Modfield’] [‘If-Modified-Since’] 304

24. def show
@user = User.find(params[:id])
if stale?(:last_modified => @user.updated_at )
@content = @user.very_expensive_call
respond_to do |format|
formant.html.erb
end
end
end
304 Not Modified

25. Database Performance

26. ADD INDEX
EXPLAIN every query, avoid table scan

27. SELECT ONLY NEED
use “scrooge” plugin replace SELECT *

28. Avoid N+1 Queries
use :include => [ “comment”]

29. Use Counter Cache
size, count , length

30. Use CONSTANT
CONSTANT will cache in memory

31. Use Transaction
BEGIN COMMIT is expensive

32. Ruby / Rails Performance

33. Writing Efficiently Ruby Code
http://ihower.tw/blog/archives/1691

34. Avoiding creating unnecessary object

35. Avoiding writing stupid code

36. str + other_str => new_str
str = “a” + “b” + “c”
==>
str = “#{a}#{b}#{c}”

37. Array#join
tag_list = [“a”, “b”, “c”]
# rendering tags
tags = “”
tag_list.each do |t|
tags +=”t”
tags += “,”
end
===>
tags = tag_list.join(“,”)

38. tag_list = [“a”, “b”, “c”] Array#each_with_index
# rendering tags
tags = “”
counter = 1
tag_list.each do |t|
tags +=”counter”
tags +=”t”
tags += “,”
counter +=1
end
===>
tag_list.each_with_index do |t , i|

39. Date.parse(“1992-02-13”)
very expensive, should use regexp

40. Knowing Rails API

41. render :partial is slow
Use Fragment Caching

42. Rails action is expensive
Use Rails Metal

43. Ruby API is slow
use C extension

44. Conculsion

45. • Cache Everything
• Knowing API
• Drop in other language / system command
• Avoid hit DB
• Avoid hit Application

46. Thanks for listening