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diff --git a/guides/source/performance_testing.md b/guides/source/performance_testing.md deleted file mode 100644 index 6bc175d3b6..0000000000 --- a/guides/source/performance_testing.md +++ /dev/null @@ -1,676 +0,0 @@ -Performance Testing Rails Applications -====================================== - -This guide covers the various ways of performance testing a Ruby on Rails -application. - -After reading this guide, you will know: - -* The various types of benchmarking and profiling metrics. -* How to generate performance and benchmarking tests. -* How to install and use a GC-patched Ruby binary to measure memory usage and object - allocation. -* The benchmarking information provided by Rails inside the log files. -* Various tools facilitating benchmarking and profiling. - -Performance testing is an integral part of the development cycle. It is very -important that you don't make your end users wait for too long before the page -is completely loaded. Ensuring a pleasant browsing experience for end users and -cutting the cost of unnecessary hardware is important for any non-trivial web -application. - --------------------------------------------------------------------------------- - -Performance Test Cases ----------------------- - -Rails performance tests are a special type of integration tests, designed for -benchmarking and profiling the test code. With performance tests, you can -determine where your application's memory or speed problems are coming from, -and get a more in-depth picture of those problems. - -In a freshly generated Rails application, `test/performance/browsing_test.rb` -contains an example of a performance test: - -```ruby -require 'test_helper' -require 'rails/performance_test_help' - -class BrowsingTest < ActionDispatch::PerformanceTest - # Refer to the documentation for all available options - # self.profile_options = { runs: 5, metrics: [:wall_time, :memory], - # output: 'tmp/performance', formats: [:flat] } - - test "homepage" do - get '/' - end -end -``` - -This example is a simple performance test case for profiling a GET request to -the application's homepage. - -### Generating Performance Tests - -Rails provides a generator called `performance_test` for creating new -performance tests: - -```bash -$ rails generate performance_test homepage -``` - -This generates `homepage_test.rb` in the `test/performance` directory: - -```ruby -require 'test_helper' -require 'rails/performance_test_help' - -class HomepageTest < ActionDispatch::PerformanceTest - # Refer to the documentation for all available options - # self.profile_options = { runs: 5, metrics: [:wall_time, :memory], - # output: 'tmp/performance', formats: [:flat] } - - test "homepage" do - get '/' - end -end -``` - -### Examples - -Let's assume your application has the following controller and model: - -```ruby -# routes.rb -root to: 'home#dashboard' -resources :posts - -# home_controller.rb -class HomeController < ApplicationController - def dashboard - @users = User.last_ten.includes(:avatars) - @posts = Post.all_today - end -end - -# posts_controller.rb -class PostsController < ApplicationController - def create - @post = Post.create(params[:post]) - redirect_to(@post) - end -end - -# post.rb -class Post < ActiveRecord::Base - before_save :recalculate_costly_stats - - def slow_method - # I fire gallzilion queries sleeping all around - end - - private - - def recalculate_costly_stats - # CPU heavy calculations - end -end -``` - -#### Controller Example - -Because performance tests are a special kind of integration test, you can use -the `get` and `post` methods in them. - -Here's the performance test for `HomeController#dashboard` and -`PostsController#create`: - -```ruby -require 'test_helper' -require 'rails/performance_test_help' - -class PostPerformanceTest < ActionDispatch::PerformanceTest - def setup - # Application requires logged-in user - login_as(:lifo) - end - - test "homepage" do - get '/dashboard' - end - - test "creating new post" do - post '/posts', post: { body: 'lifo is fooling you' } - end -end -``` - -You can find more details about the `get` and `post` methods in the -[Testing Rails Applications](testing.html) guide. - -#### Model Example - -Even though the performance tests are integration tests and hence closer to -the request/response cycle by nature, you can still performance test pure model -code. - -Performance test for `Post` model: - -```ruby -require 'test_helper' -require 'rails/performance_test_help' - -class PostModelTest < ActionDispatch::PerformanceTest - test "creation" do - Post.create body: 'still fooling you', cost: '100' - end - - test "slow method" do - # Using posts(:awesome) fixture - posts(:awesome).slow_method - end -end -``` - -### Modes - -Performance tests can be run in two modes: Benchmarking and Profiling. - -#### Benchmarking - -Benchmarking makes it easy to quickly gather a few metrics about each test run. -By default, each test case is run **4 times** in benchmarking mode. - -To run performance tests in benchmarking mode: - -```bash -$ rake test:benchmark -``` - -#### Profiling - -Profiling allows you to make an in-depth analysis of each of your tests by using -an external profiler. Depending on your Ruby interpreter, this profiler can be -native (Rubinius, JRuby) or not (MRI, which uses RubyProf). By default, each -test case is run **once** in profiling mode. - -To run performance tests in profiling mode: - -```bash -$ rake test:profile -``` - -### Metrics - -Benchmarking and profiling run performance tests and give you multiple metrics. -The availability of each metric is determined by the interpreter being used—none -of them support all metrics—and by the mode in use. A brief description of each -metric and their availability across interpreters/modes is given below. - -#### Wall Time - -Wall time measures the real world time elapsed during the test run. It is -affected by any other processes concurrently running on the system. - -#### Process Time - -Process time measures the time taken by the process. It is unaffected by any -other processes running concurrently on the same system. Hence, process time -is likely to be constant for any given performance test, irrespective of the -machine load. - -#### CPU Time - -Similar to process time, but leverages the more accurate CPU clock counter -available on the Pentium and PowerPC platforms. - -#### User Time - -User time measures the amount of time the CPU spent in user-mode, i.e. within -the process. This is not affected by other processes and by the time it possibly -spends blocked. - -#### Memory - -Memory measures the amount of memory used for the performance test case. - -#### Objects - -Objects measures the number of objects allocated for the performance test case. - -#### GC Runs - -GC Runs measures the number of times GC was invoked for the performance test case. - -#### GC Time - -GC Time measures the amount of time spent in GC for the performance test case. - -#### Metric Availability - -##### Benchmarking - -| Interpreter | Wall Time | Process Time | CPU Time | User Time | Memory | Objects | GC Runs | GC Time | -| ------------ | --------- | ------------ | -------- | --------- | ------ | ------- | ------- | ------- | -| **MRI** | yes | yes | yes | no | yes | yes | yes | yes | -| **REE** | yes | yes | yes | no | yes | yes | yes | yes | -| **Rubinius** | yes | no | no | no | yes | yes | yes | yes | -| **JRuby** | yes | no | no | yes | yes | yes | yes | yes | - -##### Profiling - -| Interpreter | Wall Time | Process Time | CPU Time | User Time | Memory | Objects | GC Runs | GC Time | -| ------------ | --------- | ------------ | -------- | --------- | ------ | ------- | ------- | ------- | -| **MRI** | yes | yes | no | no | yes | yes | yes | yes | -| **REE** | yes | yes | no | no | yes | yes | yes | yes | -| **Rubinius** | yes | no | no | no | no | no | no | no | -| **JRuby** | yes | no | no | no | no | no | no | no | - -NOTE: To profile under JRuby you'll need to run `export JRUBY_OPTS="-Xlaunch.inproc=false --profile.api"` -**before** the performance tests. - -### Understanding the Output - -Performance tests generate different outputs inside `tmp/performance` directory -depending on their mode and metric. - -#### Benchmarking - -In benchmarking mode, performance tests generate two types of outputs. - -##### Command Line - -This is the primary form of output in benchmarking mode. Example: - -```bash -BrowsingTest#test_homepage (31 ms warmup) - wall_time: 6 ms - memory: 437.27 KB - objects: 5,514 - gc_runs: 0 - gc_time: 19 ms -``` - -##### CSV Files - -Performance test results are also appended to `.csv` files inside `tmp/performance`. -For example, running the default `BrowsingTest#test_homepage` will generate -following five files: - -* BrowsingTest#test_homepage_gc_runs.csv -* BrowsingTest#test_homepage_gc_time.csv -* BrowsingTest#test_homepage_memory.csv -* BrowsingTest#test_homepage_objects.csv -* BrowsingTest#test_homepage_wall_time.csv - -As the results are appended to these files each time the performance tests are -run in benchmarking mode, you can collect data over a period of time. This can -be very helpful in analyzing the effects of code changes. - -Sample output of `BrowsingTest#test_homepage_wall_time.csv`: - -```bash -measurement,created_at,app,rails,ruby,platform -0.00738224999999992,2009-01-08T03:40:29Z,,3.0.0,ruby-1.8.7.249,x86_64-linux -0.00755874999999984,2009-01-08T03:46:18Z,,3.0.0,ruby-1.8.7.249,x86_64-linux -0.00762099999999993,2009-01-08T03:49:25Z,,3.0.0,ruby-1.8.7.249,x86_64-linux -0.00603075000000008,2009-01-08T04:03:29Z,,3.0.0,ruby-1.8.7.249,x86_64-linux -0.00619899999999995,2009-01-08T04:03:53Z,,3.0.0,ruby-1.8.7.249,x86_64-linux -0.00755449999999991,2009-01-08T04:04:55Z,,3.0.0,ruby-1.8.7.249,x86_64-linux -0.00595999999999997,2009-01-08T04:05:06Z,,3.0.0,ruby-1.8.7.249,x86_64-linux -0.00740450000000004,2009-01-09T03:54:47Z,,3.0.0,ruby-1.8.7.249,x86_64-linux -0.00603150000000008,2009-01-09T03:54:57Z,,3.0.0,ruby-1.8.7.249,x86_64-linux -0.00771250000000012,2009-01-09T15:46:03Z,,3.0.0,ruby-1.8.7.249,x86_64-linux -``` - -#### Profiling - -In profiling mode, performance tests can generate multiple types of outputs. -The command line output is always presented but support for the others is -dependent on the interpreter in use. A brief description of each type and -their availability across interpreters is given below. - -##### Command Line - -This is a very basic form of output in profiling mode: - -```bash -BrowsingTest#test_homepage (58 ms warmup) - process_time: 63 ms - memory: 832.13 KB - objects: 7,882 -``` - -##### Flat - -Flat output shows the metric—time, memory, etc—measure in each method. -[Check Ruby-Prof documentation for a better explanation](http://ruby-prof.rubyforge.org/files/examples/flat_txt.html). - -##### Graph - -Graph output shows the metric measure in each method, which methods call it and -which methods it calls. [Check Ruby-Prof documentation for a better explanation](http://ruby-prof.rubyforge.org/files/examples/graph_txt.html). - -##### Tree - -Tree output is profiling information in calltree format for use by [kcachegrind](http://kcachegrind.sourceforge.net/html/Home.html) -and similar tools. - -##### Output Availability - -| | Flat | Graph | Tree | -| ------------ | ---- | ----- | ---- | -| **MRI** | yes | yes | yes | -| **REE** | yes | yes | yes | -| **Rubinius** | yes | yes | no | -| **JRuby** | yes | yes | no | - -### Tuning Test Runs - -Test runs can be tuned by setting the `profile_options` class variable on your -test class. - -```ruby -require 'test_helper' -require 'rails/performance_test_help' - -class BrowsingTest < ActionDispatch::PerformanceTest - self.profile_options = { runs: 5, metrics: [:wall_time, :memory] } - - test "homepage" - get '/' - end -end -``` - -In this example, the test would run 5 times and measure wall time and memory. -There are a few configurable options: - -| Option | Description | Default | Mode | -| ---------- | ------------------------------------------ | ----------------------------- | --------- | -| `:runs` | Number of runs. | Benchmarking: 4, Profiling: 1 | Both | -| `:output` | Directory to use when writing the results. | `tmp/performance` | Both | -| `:metrics` | Metrics to use. | See below. | Both | -| `:formats` | Formats to output to. | See below. | Profiling | - -Metrics and formats have different defaults depending on the interpreter in use. - -| Interpreter | Mode | Default metrics | Default formats | -| -------------- | ------------ | ------------------------------------------------------- | ----------------------------------------------- | -| **MRI/REE** | Benchmarking | `[:wall_time, :memory, :objects, :gc_runs, :gc_time]` | N/A | -| | Profiling | `[:process_time, :memory, :objects]` | `[:flat, :graph_html, :call_tree, :call_stack]` | -| **Rubinius** | Benchmarking | `[:wall_time, :memory, :objects, :gc_runs, :gc_time]` | N/A | -| | Profiling | `[:wall_time]` | `[:flat, :graph]` | -| **JRuby** | Benchmarking | `[:wall_time, :user_time, :memory, :gc_runs, :gc_time]` | N/A | -| | Profiling | `[:wall_time]` | `[:flat, :graph]` | - -As you've probably noticed by now, metrics and formats are specified using a -symbol array with each name [underscored.](http://api.rubyonrails.org/classes/String.html#method-i-underscore) - -### Performance Test Environment - -Performance tests are run in the `test` environment. But running performance -tests will set the following configuration parameters: - -```bash -ActionController::Base.perform_caching = true -ActiveSupport::Dependencies.mechanism = :require -Rails.logger.level = ActiveSupport::Logger::INFO -``` - -As `ActionController::Base.perform_caching` is set to `true`, performance tests -will behave much as they do in the `production` environment. - -### Installing GC-Patched MRI - -To get the best from Rails' performance tests under MRI, you'll need to build -a special Ruby binary with some super powers. - -The recommended patches for MRI can be found on [RVM's _patches_ directory](https://github.com/wayneeseguin/rvm/tree/master/patches/ruby) -under each specific interpreter version. - -Concerning the installation itself, you can either do this easily by using -[RVM](https://rvm.io/) or you can build everything from source, -which is a little bit harder. - -#### Install Using RVM - -The process of installing a patched Ruby interpreter is very easy if you let RVM -do the hard work. All of the following RVM commands will provide you with a -patched Ruby interpreter: - -```bash -$ rvm install 1.9.2-p180 --patch gcdata -$ rvm install 1.9.2-p180 --patch ~/Downloads/downloaded_gcdata_patch.patch -``` - -You can even keep your regular interpreter by assigning a name to the patched -one: - -```bash -$ rvm install 1.9.2-p180 --patch gcdata --name gcdata -$ rvm use 1.9.2-p180 # your regular ruby -$ rvm use 1.9.2-p180-gcdata # your patched ruby -``` - -And it's done! You have installed a patched Ruby interpreter. - -#### Install From Source - -This process is a bit more complicated, but straightforward nonetheless. If -you've never compiled a Ruby binary before, follow these steps to build a -Ruby binary inside your home directory. - -##### Download and Extract - -```bash -$ mkdir rubygc -$ wget <the version you want from ftp://ftp.ruby-lang.org/pub/ruby> -$ tar -xzvf <ruby-version.tar.gz> -$ cd <ruby-version> -``` - -##### Apply the Patch - -```bash -$ curl https://raw.github.com/wayneeseguin/rvm/master/patches/ruby/1.9.2/p180/gcdata.patch | patch -p0 # if you're on 1.9.2! -``` - -##### Configure and Install - -The following will install Ruby in your home directory's `/rubygc` directory. -Make sure to replace `<homedir>` with a full patch to your actual home -directory. - -```bash -$ ./configure --prefix=/<homedir>/rubygc -$ make && make install -``` - -##### Prepare Aliases - -For convenience, add the following lines in your `~/.profile`: - -```bash -alias gcruby='~/rubygc/bin/ruby' -alias gcrake='~/rubygc/bin/rake' -alias gcgem='~/rubygc/bin/gem' -alias gcirb='~/rubygc/bin/irb' -alias gcrails='~/rubygc/bin/rails' -``` - -Don't forget to use your aliases from now on. - -### Using Ruby-Prof on MRI and REE - -Add Ruby-Prof to your applications' Gemfile if you want to benchmark/profile -under MRI or REE: - -```ruby -gem 'ruby-prof' -``` - -Now run `bundle install` and you're ready to go. - -Command Line Tools ------------------- - -Writing performance test cases could be an overkill when you are looking for one -time tests. Rails ships with two command line tools that enable quick and dirty -performance testing: - -### `benchmarker` - -Usage: - -```bash -Usage: rails benchmarker 'Ruby.code' 'Ruby.more_code' ... [OPTS] - -r, --runs N Number of runs. - Default: 4 - -o, --output PATH Directory to use when writing the results. - Default: tmp/performance - -m, --metrics a,b,c Metrics to use. - Default: wall_time,memory,objects,gc_runs,gc_time -``` - -Example: - -```bash -$ rails benchmarker 'Item.all' 'CouchItem.all' --runs 3 --metrics wall_time,memory -``` - -### `profiler` - -Usage: - -```bash -Usage: rails profiler 'Ruby.code' 'Ruby.more_code' ... [OPTS] - -r, --runs N Number of runs. - Default: 1 - -o, --output PATH Directory to use when writing the results. - Default: tmp/performance - -m, --metrics a,b,c Metrics to use. - Default: process_time,memory,objects - -f, --formats x,y,z Formats to output to. - Default: flat,graph_html,call_tree -``` - -Example: - -```bash -$ rails profiler 'Item.all' 'CouchItem.all' --runs 2 --metrics process_time --formats flat -``` - -NOTE: Metrics and formats vary from interpreter to interpreter. Pass `--help` to -each tool to see the defaults for your interpreter. - -Helper Methods --------------- - -Rails provides various helper methods inside Active Record, Action Controller -and Action View to measure the time taken by a given piece of code. The method -is called `benchmark()` in all the three components. - -### Model - -```ruby -Project.benchmark("Creating project") do - project = Project.create("name" => "stuff") - project.create_manager("name" => "David") - project.milestones << Milestone.all -end -``` - -This benchmarks the code enclosed in the `Project.benchmark("Creating project") do...end` -block and prints the result to the log file: - -```ruby -Creating project (185.3ms) -``` - -Please refer to the [API docs](http://api.rubyonrails.org/classes/ActiveSupport/Benchmarkable.html#method-i-benchmark) -for additional options to `benchmark()`. - -### Controller - -Similarly, you could use this helper method inside [controllers.](http://api.rubyonrails.org/classes/ActiveSupport/Benchmarkable.html) - -```ruby -def process_projects - benchmark("Processing projects") do - Project.process(params[:project_ids]) - Project.update_cached_projects - end -end -``` - -NOTE: `benchmark` is a class method inside controllers. - -### View - -And in [views](http://api.rubyonrails.org/classes/ActiveSupport/Benchmarkable.html:) - -```erb -<% benchmark("Showing projects partial") do %> - <%= render @projects %> -<% end %> -``` - -Request Logging ---------------- - -Rails log files contain very useful information about the time taken to serve -each request. Here's a typical log file entry: - -```bash -Processing ItemsController#index (for 127.0.0.1 at 2009-01-08 03:06:39) [GET] -Rendering template within layouts/items -Rendering items/index -Completed in 5ms (View: 2, DB: 0) | 200 OK [http://0.0.0.0/items] -``` - -For this section, we're only interested in the last line: - -```bash -Completed in 5ms (View: 2, DB: 0) | 200 OK [http://0.0.0.0/items] -``` - -This data is fairly straightforward to understand. Rails uses millisecond(ms) as -the metric to measure the time taken. The complete request spent 5 ms inside -Rails, out of which 2 ms were spent rendering views and none was spent -communication with the database. It's safe to assume that the remaining 3 ms -were spent inside the controller. - -Michael Koziarski has an [interesting blog post](http://www.therailsway.com/2009/1/6/requests-per-second) -explaining the importance of using milliseconds as the metric. - -Useful Links ------------- - -### Rails Plugins and Gems - -* [Rails Analyzer](http://rails-analyzer.rubyforge.org) -* [Rails Footnotes](https://github.com/josevalim/rails-footnotes/tree/master) -* [Query Reviewer](https://github.com/nesquena/query_reviewer) -* [MiniProfiler](http://www.miniprofiler.com) - -### Generic Tools - -* [httperf](http://www.hpl.hp.com/research/linux/httperf/) -* [ab](http://httpd.apache.org/docs/2.2/programs/ab.html) -* [JMeter](http://jakarta.apache.org/jmeter/) -* [kcachegrind](http://kcachegrind.sourceforge.net/html/Home.html) - -### Tutorials and Documentation - -* [ruby-prof API Documentation](http://ruby-prof.rubyforge.org) -* [Request Profiling Railscast](http://railscasts.com/episodes/98-request-profiling) - Outdated, but useful for understanding call graphs. - -Commercial Products -------------------- - -Rails has been lucky to have a few companies dedicated to Rails-specific -performance tools. A couple of those are: - -* [New Relic](http://www.newrelic.com) -* [Scout](http://scoutapp.com) |