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authorRafael Mendonça França <rafaelmfranca@gmail.com>2015-08-10 16:53:08 -0300
committerRafael Mendonça França <rafaelmfranca@gmail.com>2015-08-10 16:53:08 -0300
commitc14c798298e4cb058c6bdda9ceacb61a59a072b4 (patch)
treeff80b388b837b14ad57b27d79fe7ca1c05308d4f
parent8e014f28ccd380328f49075b62f23322c49033c2 (diff)
parent0d8b552c684b25c2c8993ddd3430434fec890b16 (diff)
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Merge pull request #21188 from derekprior/dp-asset-host-docs
Update info on browser connection limits [ci skip]
-rw-r--r--actionview/lib/action_view/helpers/asset_url_helper.rb29
1 files changed, 18 insertions, 11 deletions
diff --git a/actionview/lib/action_view/helpers/asset_url_helper.rb b/actionview/lib/action_view/helpers/asset_url_helper.rb
index 3beb7fefb1..28417fdc80 100644
--- a/actionview/lib/action_view/helpers/asset_url_helper.rb
+++ b/actionview/lib/action_view/helpers/asset_url_helper.rb
@@ -31,26 +31,33 @@ module ActionView
# stylesheet_link_tag("application")
# # => <link href="http://assets.example.com/assets/application.css" media="screen" rel="stylesheet" />
#
- # Browsers typically open at most two simultaneous connections to a single
- # host, which means your assets often have to wait for other assets to finish
- # downloading. You can alleviate this by using a <tt>%d</tt> wildcard in the
- # +asset_host+. For example, "assets%d.example.com". If that wildcard is
- # present Rails distributes asset requests among the corresponding four hosts
- # "assets0.example.com", ..., "assets3.example.com". With this trick browsers
- # will open eight simultaneous connections rather than two.
+ # Browsers open a limited number of simulataneous connections to a single
+ # host. The exact number varies by browser and version. This limit may cause
+ # some asset downloads to wait for previous assets to finish before they can
+ # begin. You can use the <tt>%d</tt> wildcard in the +asset_host+ to
+ # distribute the requests over four hosts. For example,
+ # <tt>assets%d.example.com<tt> will spread the asset requests over
+ # "assets0.example.com", ..., "assets3.example.com".
#
# image_tag("rails.png")
# # => <img alt="Rails" src="http://assets0.example.com/assets/rails.png" />
# stylesheet_link_tag("application")
# # => <link href="http://assets2.example.com/assets/application.css" media="screen" rel="stylesheet" />
#
- # To do this, you can either setup four actual hosts, or you can use wildcard
- # DNS to CNAME the wildcard to a single asset host. You can read more about
- # setting up your DNS CNAME records from your ISP.
+ # This may improve the asset loading performance of your application.
+ # It is also possible the combination of additional connection overhead
+ # (DNS, SSL) and the overall browser connection limits may result in this
+ # solution being slower. You should be sure to measure your actual
+ # performance across targeted browers both before and after this change.
+ #
+ # To implement the corresponding hosts you can either setup four actual
+ # hosts or use wildcard DNS to CNAME the wilcard to a single asset host.
+ # You can read more about setting up your DNS CNAME records from your ISP.
#
# Note: This is purely a browser performance optimization and is not meant
# for server load balancing. See http://www.die.net/musings/page_load_time/
- # for background.
+ # for background and http://www.browserscope.org/?category=network for
+ # connection limit data.
#
# Alternatively, you can exert more control over the asset host by setting
# +asset_host+ to a proc like this: