Dial

A modern profiler for your Rails application.

Utilizes vernier for profiling and prosopite for N+1 query detection.

Note

Check out the resources in the vernier project for more information on how to interpret the viewer, as well as comparisons with other profilers, including stackprof.

Installation

1. Add the gem to your Rails application's Gemfile:

group :development do
  gem "dial"
end

2. Install the gem:

bundle install

3. Mount the engine in your config/routes.rb file:

# this will mount the engine at /dial
mount Dial::Engine, at: "/" if Rails.env.development?

4. (Optional) Configure the gem in an initializer:

# config/initializers/dial.rb

Dial.configure do |config|
  config.sampling_percentage = 50
  config.storage = Dial::Storage::RedisAdapter
  config.storage_options = { client: Redis.new(url: ENV["REDIS_URL"]), ttl: 86400 }
  config.vernier_interval = 100
  config.vernier_allocation_interval = 10_000
  config.prosopite_ignore_queries += [/pg_sleep/i]
end

Options

Option	Description	Default
sampling_percentage	Percentage of requests to profile.	100 in development, 1 in production
storage	Storage adapter class for profile data	Dial::Storage::FileAdapter
storage_options	Options hash passed to storage adapter	{ ttl: 3600 }
content_security_policy_nonce	Sets the content security policy nonce to use when inserting Dial's script. Can be a string, or a Proc which receives env and response headers as arguments and returns the nonce string.	Rails generated nonce or nil
vernier_interval	Sets the interval option for vernier.	200
vernier_allocation_interval	Sets the allocation_interval option for vernier.	2_000
prosopite_ignore_queries	Sets the ignore_queries option for prosopite.	[/schema_migrations/i]

Storage Backends

File Storage (Default)

Profile data is stored as files on disk with polled expiration. Only suitable for development and single-server deployments.

Dial.configure do |config|
  config.storage = Dial::Storage::FileAdapter
  config.storage_options = { ttl: 86400 }
end

Redis Storage

Profile data is stored in Redis with automatic expiration. Supports both single Redis instances and Redis Cluster.

# Single Redis instance
Dial.configure do |config|
  config.storage = Dial::Storage::RedisAdapter
  config.storage_options = { client: Redis.new(url: "redis://localhost:6379"), ttl: 86400 }
end

# Redis Cluster
Dial.configure do |config|
  config.storage = Dial::Storage::RedisAdapter
  config.storage_options = {
    client: Redis::Cluster.new(nodes: [
      "redis://node1:7000",
      "redis://node2:7001",
      "redis://node3:7002"
    ]),
    ttl: 86400
  }
end

Memcached Storage

Profile data is stored in Memcached with automatic expiration.

Dial.configure do |config|
  config.storage = Dial::Storage::MemcachedAdapter
  config.storage_options = { client: Dalli::Client.new("localhost:11211"), ttl: 86400 }
end

Comparison with rack-mini-profiler

	rack-mini-profiler	Dial
Compatibility	Any Rack application	Only Rails applications
Database Profiling	Yes	Yes (via vernier hook - marker table, chart)
N+1 Query Detection	Yes (*needs to be inferred)	Yes (via prosopite)
Ruby Profiling	Yes (with stackprof - flame graph)	Yes (via vernier - flame graph, stack chart, call tree)
Ruby Allocation Profiling	Yes (with stackprof - flame graph)	Yes (via vernier - flame graph, stack chart, call tree)
Memory Profiling	Yes (with memory_profiler)	Yes (*overall usage only) (via vernier hook - graph)
View Profiling	Yes	Yes (via vernier hook - marker table, chart)
Snapshot Sampling	Yes	No
Storage Backends	Redis, Memcached, File, Memory	Redis, Memcached, File
Production Ready	Yes	Yes

Note

SQL queries displayed in the profile are not annotated with the caller location by default. If you're not using the marginalia gem to annotate your queries, you will need to extend your application's ActiveRecord QueryLogs yourself.

Development

After checking out the repo, run bin/setup to install dependencies. Then, run bundle exec rake test to run the tests. You can also run bin/console for an interactive prompt that will allow you to experiment.

Testing Storage Adapters

To test the Redis and Memcached storage adapters, you'll need running instances: docker compose -f docker-compose.storage.yml up

Contributing

Bug reports and pull requests are welcome on GitHub at https://github.com/joshuay03/dial.

License

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

Code of Conduct

Everyone interacting in the Dial project's codebase and issue tracker is expected to follow the code of conduct.