Rack::Latency

10:06:49 web.1  | at=info source=yahoo measure#response.size=9 measure#response.latency=130.86ms
10:06:53 web.1  | at=info source=google measure#response.size=11 measure#response.latency=60.65ms
10:06:53 web.1  | at=info source=yahoo measure#response.size=9 measure#response.latency=122.92ms
10:06:57 web.1  | at=info source=google measure#response.size=11 measure#response.latency=53.46ms
10:06:57 web.1  | at=info source=yahoo measure#response.size=9 measure#response.latency=129.75ms
10:07:01 web.1  | at=info source=google measure#response.size=11 measure#response.latency=58.56ms

This gem measures request latency to other hosts. It runs as a separate thread created by its own middleware. If you're running multiple apps that talk to each other, it's a good way to sniff out potential network problems.

On my system, the head measurement times are roughly equivalent to (maybe 10-20% faster than) curl -I.

Installation and Configuration

Add gem 'rack-latency' to your app's Gemfile. Then create an initializer to specify your desired measurements:

# config/initializers/rack-latency.rb
Rack::Latency.configure do |measure|
  # time a HEAD request for google.com.
  measure.head "http://www.google.com/" 

  # time a GET request to a Yahoo IP, and rename the measurement to "yahoo".
  measure.get "http://98.138.253.109/", name: "yahoo" 

  # set the delay time between measurement loops.
  measure.wait ENV["RACK-LATENCY-WAIT"] || 4

  # set the environment(s) in which to run, as defined by Rails.env or RACK_ENV.
  # By default, it will only run in production.
  measure.environment :production
  # or
  measure.environments :production, :staging
end

Contributing

Fork it ( http://github.com//rack-latency/fork )
Create your feature branch (git checkout -b my-new-feature)
Commit your changes (git commit -am 'Add some feature')
Push to the branch (git push origin my-new-feature)
Create new Pull Request