CODEWITHSUNDEEP
ruby-on-railsruby
salt.racer
salt.racer

Reputation: 22332

Profile a rails controller action

What is the best way to profile a controller action in Ruby on Rails. Currently I am using the brute-force method of throwing in puts Time.now calls between what I think will be a bottleneck. But that feels really, really dirty. There has got to be a better way.

Upvotes: 33

Views: 13065

Answers (5)

Rob Davis
Rob Davis

Reputation: 15772

I picked up this technique a while back and have found it quite handy.

When it's in place, you can add ?profile=true to any URL that hits a controller. Your action will run as usual, but instead of delivering the rendered page to the browser, it'll send a detailed, nicely formatted ruby-prof page that shows where your action spent its time.

First, add ruby-prof to your Gemfile, probably in the development group:

group :development do
    gem "ruby-prof"
end

Then add an around filter to your ApplicationController:

around_action :performance_profile if Rails.env == 'development'

def performance_profile
  if params[:profile] && result = RubyProf.profile { yield }

    out = StringIO.new
    RubyProf::GraphHtmlPrinter.new(result).print out, :min_percent => 0
    self.response_body = out.string

  else
    yield
  end
end

Reading the ruby-prof output is a bit of an art, but I'll leave that as an exercise.

Additional note by ScottJShea: If you want to change the measurement type place this:

RubyProf.measure_mode = RubyProf::GC_TIME #example

Before the if in the profile method of the application controller. You can find a list of the available measurements at the ruby-prof page. As of this writing the memory and allocations data streams seem to be corrupted (see defect).

Upvotes: 44

Minqi Pan
Minqi Pan

Reputation: 2801

This works in Rails 4.2.6:

    o=OpenStruct.new(logger: Rails.logger)
    o.extend ActiveSupport::Benchmarkable
    o.benchmark 'name' do
      # ... your code ...
    end

Upvotes: -1

John Topley
John Topley

Reputation: 115292

You might want to give the FiveRuns TuneUp service a try, as it's really rather impressive. Disclaimer: I'm not associated with FiveRuns in any way, I've just tried this service out.

TuneUp is a free service whereby you download a plugin and when you run your application it injects a panel at the top of the screen that can be expanded to display detailed performance metrics.

It gives you some nice graphs, including one that shows what proportion of time is spent in the Model, View and Controller. You can even drill right down to see the individual SQL queries that ActiveRecord is executing if you need to and it can show you the underlying database schema with another click.

Finally, you can optionally upload your profiling data to the FiveRuns site for community performance analysis and advice.

Upvotes: 1

Stuart
Stuart

Reputation: 323

There's a Railscast on profiling that's well worth watching

http://railscasts.com/episodes/98-request-profiling

Upvotes: 9

Chris Bunch
Chris Bunch

Reputation: 89813

Use the Benchmark standard library and the various tests available in Rails (unit, functional, integration). Here's an example:

def test_do_something
  elapsed_time = Benchmark.realtime do
    100.downto(1) do |index|
      # do something here
    end
  end
  assert elapsed_time < SOME_LIMIT
end

So here we just do something 100 times, time it via the Benchmark library, and ensure that it took less than SOME_LIMIT amount of time.

You also may find these links useful: The Benchmark.realtime reference and the Test::Unit reference. Also, if you're into the 'book reading' thing, I picked up the idea for the example from Agile Web Development with Rails, which talks all about the different testing types and a little on performance testing.

Upvotes: 9

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