---
title: "Profiling"
description: "Learn how to enable profiling in your app if it is not already set up."
url: https://docs.sentry.io/platforms/ruby/guides/rack/profiling/
---

# Set Up Profiling | Sentry for Rack Middleware

Ruby Profiling is currently in beta. Beta features are still in progress and may have bugs. We recognize the irony.

With [profiling](https://docs.sentry.io/product/explore/profiling.md), Sentry tracks your software's performance by sampling your program's call stack in a variety of environments. This feature collects function-level information about your code and enables you to fine-tune your program's performance. [Sentry's profiler](https://sentry.io/for/profiling/) captures function calls and their exact locations, aggregates them, and shows you the most common code paths of your program. This highlights areas you could optimize to help increase both the performance of your code and increase user satisfaction, as well as drive down costs.

## [Enable Profiling using StackProf](https://docs.sentry.io/platforms/ruby/guides/rack/profiling.md#enable-profiling-using-stackprof)

StackProf profiling beta is available starting in SDK version `5.9.0`.

We use the [`stackprof` gem](https://github.com/tmm1/stackprof) to collect profiles for Ruby.

First add `stackprof` to your `Gemfile` and make sure it is loaded before `sentry-ruby`.

```ruby
# Gemfile

gem 'stackprof'
gem 'sentry-ruby'
```

Then, make sure both `traces_sample_rate` and `profiles_sample_rate` are set and non-zero in your Sentry initializer.

```ruby
# config/initializers/sentry.rb

Sentry.init do |config|
  config.dsn = "___PUBLIC_DSN___"
  config.traces_sample_rate = 1.0
  config.profiles_sample_rate = 1.0
end
```

The `profiles_sample_rate` setting is *relative* to the `traces_sample_rate` setting.

For Profiling to work, you have to first enable Sentry’s tracing via `traces_sample_rate` (like in the example above). Read our [tracing setup documentation](https://docs.sentry.io/platforms/ruby/guides/rack/tracing.md) to learn how to configure sampling. If you set your sample rate to 1.0, all transactions will be captured.

## [Enable Profiling using Vernier](https://docs.sentry.io/platforms/ruby/guides/rack/profiling.md#enable-profiling-using-vernier)

Vernier profiling beta is available starting in SDK version `5.21.0`.

Vernier requires Ruby 3.2.1+

You can have much better profiles if you're using multi-threaded servers like Puma now by leveraging Vernier.

First, add `vernier` to your `Gemfile` and make sure it is loaded before `sentry-ruby`.

```ruby
# Gemfile

gem 'vernier'
gem 'sentry-ruby'
```

Then, set a `profiles_sample_rate` and the new `profiler_class` configuration in your sentry initializer to use the new profiler.

```ruby
# config/initializers/sentry.rb

Sentry.init do |config|
  config.dsn = "___PUBLIC_DSN___"
  config.profiles_sample_rate = 1.0
  config.traces_sample_rate = 1.0
  config.profiler_class = Sentry::Vernier::Profiler
end
```