Rails Mini Profiler

Performance profiling for Rails, made simple.

What's this?

Rails Mini Profiler is an easy-to-use performance profiler for your Rails applications. It is heavily inspired by Rack Mini Profiler and other APM tools. Check out a short video preview below:

Note: This gem is in early development and I'm looking for contributors. Try it out and leave some feedback, it really goes a long way in helping me out with development. Any feature request or bug report is welcome. If you like this project, leave a star to show your support! ⭐

Getting Started

Add Rails Mini Profiler to your Gemfile:

gem 'rails_mini_profiler'

Install the gem and run the installer:

bundle install
rails rails_mini_profiler:install

Inspect the generated migration in db/migrate and run it:

rails db:migrate

Start your Rails application and perform some requests. You can either click the little hedgehog 🦔 on the top right or navigate to /rails_mini_profiler to view collected performance metrics.

Usage

Rails Mini Profiler provides detailed information about your requests to help you figure out why certain requests perform poorly.

Installing it will generate a new initializer config/initializers/rails_mini_profiler.rb and add a new route:

# routes.rb
Rails.application.routes.draw do
  ...

  mount RailsMiniProfiler::Engine => '/rails_mini_profiler'
end

Once you perform requests against your applications you can inspect them using that route, or by clicking the badge on the top right that is injected into your pages.

Request Overview

Requests to your application will be profiled automatically. You can view all stored requests by navigating to yourapp/rails_mini_profiler/profiled_requests.

Request Details

       

This view shows you how your requests spend their time. How much of it is spent in the DB, how much in rendering views? By clicking on individual traces you can find out detailed information.

Flamegraphs

Rails Mini Profiler per default records Flamegraphs for every profiled request for convenience. Note that Flamegraphs recording incur a significant performance penalty, and can take up a lot of space.

To change the default behavior see Configuration.

Flamegraphs are rendered using Speedscope. If Flamegraphs are not rendering you may have to amend your content security policy. See Troubleshooting

Configuration

You can set the following configuration options in Rails Mini Profiler:

Option	Default	Description
enabled	true (dev)/ false (prod)	Whether or not RMP is enabled
badge_enabled	true	Should the hedgehog 🦔 badge be injected into pages?
badge_position	'top-left'	Where to display the badge. Options are 'top-left', 'top-right', 'bottom-left, 'bottom-right'
flamegraph_enabled	true	Should flamegraphs be recorded automatically?
flamegraph_sample_rate	0.5	The flamegraph sample rate. How many snapshots per millisecond are created.
skip_paths	[]	An array of request paths that should not be profiled. Regex allowed.
storage	Storage	Storage configuration. See Storage
user_provider	Rack::Request.new(env).ip	How to identify users. See Users

Request Configuration

You may override the configuration by sending request parameters. The following parameters are available:

Option	Description
rmp_flamegraph	Overrides flamegraph_enabled If set to true will redirect to the flamegraph immediatly.

Storage

Rails Mini Profiler stores profiling information in your database per default. You can configure various details of how traces and requests are stored.

Configuration	Default	Description
database	nil	Set a custom database to be used for storing profiler information. Uses connect_to for profiler records
profiled_requests_table	rmp_profiled_requests	The table to be used to store profiled requests.
flamegraphs_table	rmp_flamegraphs	The table to be used to store flamegraphs.
traces_table	rmp_traces	The table to be used to store traces.

Rails Mini Profiler does not offer an automatic way to clean up old profiling information. It is recommended you add a sweeper job to clean up old profiled requests periodically (e.g. using clockwork. For example, with ActiveJob:

# Clockwork
every(1.month, 'purge rails mini profiler' do
    ProfiledRequestCleanupJob.perform_later
end

# ActiveJob
class ProfiledRequestCleanupJob < ApplicationJob
  queue_as :default

  def perform(*guests)
    RailsMiniProfiler::ProfiledRequest.where('created_at < ?', 1.month.ago).destroy_all
  end
end

Users

Profiling information is segregated by user ID. That means users cannot see each other's profiled requests.

Per default, individual users are identified by their IP address. You may change this by setting a custom user provider:

config.user_provider = proc { |env| Rack::Request.new(env).ip }

You may also explicitly set the user from the application itself:

class ApplicationController < ActionController::Base
  ...

  before_action do
    RailsMiniProfiler::User.authorize(current_user.id)
  end
end

Note that you must set the current user when running Rails Mini Profiler in production. No profiles will be saved otherwise.

Profiling in Production

Rails Mini Profiler is not intended for performance reporting. There are other tools for that ( Skylight, New Relic, DataDog...).

However, you can still use it in production to profile specific requests. Since profiling impacts performance, it is recommended that you limit which requests are being profiled:

RailsMiniProfiler.configure do |config|
  config.enabled = proc { |env| env.headers['RMP_ENABLED'].present? }
end

Only requests by explicitly set users will be stored. To configure how individual users are identified see Users

Troubleshooting

Flamegraphs are not rendering?

Flamegraphs are loaded into Speedscope using an Iframe and URI Encoded blobs (see source) If your browser gives you warnings about blocking content due to CSP you must enable blob as default source:

Rails.application.config.content_security_policy do |policy|
    policy.default_src :self, :blob
    ...
end

Some requests have no Flamegraphs attached?

StackProf, which is used for recording Flamegraphs, does not work on concurrent requests. Because of this, concurrent requests may skip recording a Flamegraph.

It is recommended that you resend only the request you wish to build a Flamegraph for.

Credit

This project was heavily inspired by projects such as rack-mini-profiler and rack-profiler. Skylight was also a huge influence.

Lena Schnedlitz designed the Logo and provided great support. Without her supreme CSS skills this project would not have been possible 🙌

Contributing

See Contributing

License

This gem is available as open source under the terms of the MIT License.