Puma server configuration in Ruby on Rails - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is Puma in the context of Rails?

Puma is a fast, concurrent web server designed to serve Ruby on Rails applications efficiently by handling multiple requests at the same time.

beginner

Where do you typically configure Puma settings in a Rails project?

Puma settings are usually configured in the config/puma.rb file inside a Rails project.

intermediate

What does the workers setting in Puma configuration control?

The workers setting controls how many separate OS processes Puma will spawn to handle requests, improving concurrency by using multiple CPU cores.

intermediate

Explain the purpose of the threads setting in Puma configuration.

The threads setting defines the minimum and maximum number of threads each Puma worker can use to handle multiple requests concurrently within a single process.

advanced

Why is it important to set preload_app! in Puma configuration when using workers?

Setting preload_app! loads the application before forking workers, which saves memory by sharing code between workers and speeds up worker boot time.

Where is Puma configuration usually found in a Rails app?

A config/routes.rb

B config/database.yml

C config/puma.rb

D app/controllers/application_controller.rb

Puma settings are placed in config/puma.rb to control server behavior.

What does the workers setting do in Puma?

A Controls logging level

B Sets number of OS processes to handle requests

C Defines maximum request size

D Sets number of database connections

workers controls how many OS processes Puma uses for concurrency.

Why use preload_app! in Puma config?

A To load the app before forking workers for memory efficiency

B To disable threading

C To increase logging verbosity

D To enable SSL encryption

preload_app! loads the app once before workers fork to save memory.

What does the threads setting specify?

A Number of database threads

B Timeout duration

C Number of workers

D Min and max threads per worker for handling requests

threads sets the thread pool size per Puma worker.

Which Puma setting helps utilize multiple CPU cores?

A workers

B threads

C port

D environment

Using multiple workers lets Puma use multiple CPU cores.

Describe how Puma uses workers and threads to handle multiple requests.

Think about how a restaurant uses multiple kitchens (workers) and multiple cooks (threads) inside each kitchen.

Explain why setting preload_app! is beneficial in Puma configuration.

Imagine preparing ingredients once before making many dishes to save time and resources.