New Relic RPM Ruby Agent
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New Relic RPM

New Relic RPM is a Ruby performance management system, developed by New Relic, Inc. RPM provides you with deep information about the performance of your Ruby on Rails or Merb application as it runs in production. The New Relic Agent is dual-purposed as a either a Rails plugin or a Gem, hosted on github and Rubyforge.

The New Relic Agent runs in one of two modes:

Developer Mode : Adds a web interface mapped to /newrelic to your application for showing detailed performance metrics on a page by page basis.

Production Mode : Low overhead instrumentation that captures detailed information on your application running in production and transmits them to where you can monitor them in real time.

Supported Environments

  • Ruby 1.8.6, 1.8.7 or 1.9.1
  • JRuby
  • Rails 1.2.6 or above
  • Merb 1.0 or above

Developer Mode

Developer mode is on by default when you run your application in the development environment (but not when it runs in other environments.) When running in developer mode, RPM will track the performance of every http request serviced by your application, and store in memory this information for the last 100 http transactions.

When running in Developer Mode, the RPM will also add a few pages to your application that allow you to analyze this performance information. (Don't worry--those pages are not added to your application's routes when you run in production mode.)

To view this performance information, including detailed SQL statement analysis, open /newrelic in your web application. For instance if you are running mongrel or thin on port 3000, enter the following into your browser:


Production Mode

When your application runs in the production environment, the New Relic agent runs in production mode. It connects to the New Relic RPM service and sends deep performance data to the RPM service for your analysis. To view this data, login to

NOTE: You must have a valid account and license key to view this data online. Refer to instructions in Getting Started, below.

Getting Started

RPM requires an agent be installed in the application as either a Rails plug-in or a gem. Both are available on RubyForge--instructions below.

To use Developer Mode, simply install the gem or plugin into your application and follow the instructions below.

To monitor your applications in production, create an account at There you can sign up for a free Lite account or one of our paid subscriptions.

Once you receive the welcome e-mail with a license key and newrelic.yml file, copy the newrelic.yml file into your app config directory.

Rails Plug-In Installation

script/plugin install

Gem Installation

sudo gem install newrelic_rpm

For Rails, edit environment.rb and add to the initalizer block:

config.gem "newrelic_rpm" 

The Developer Mode is unavailable when using the gem on Rails versions prior to 2.0.

Merb Support

To monitor a merb app install the newrelic_rpm gem and add

dependency 'newrelic_rpm'

to your init.rb file.

Current features implemented:

  • Standard monitoring, overview pages
  • Error capturing
  • Full Active Record instrumentation, including SQL explains
  • Very limited Data Mapper instrumentation
  • Transaction Traces are implemented but will not be very useful with Data Mapper until more work is done with the Data Mapper instrumentation

Still under development:

  • Developer Mode
  • Data Mapper bindings


The agent is also available on Github under newrelic/rpm. Fork away!


Reach out to us--and to fellow RPM users--at There you'll find documentation, FAQs, and forums where you can submit suggestions and discuss RPM with New Relic staff and other users.

Find a bug? E-mail, or post it to

Refer to our website for other support channels.

Thank you, and may your application scale to infinity plus one.

Lew Cirne, Founder and CEO
New Relic, Inc.