README

This is an app built for demonstration purposes for the EuRuKo 2024 conference held in Sarajevo, Bosnia & Herzegovina on September 11-13, 2024.

The application is a basic "Hacker News" style app with Users, Posts, and Comments. The seeds file will create ~100 users, ~1,000 posts, and ~10 comments per post (so ~10,000 comments). Every user has the same password: password, so you can sign in as any user to test the app.

This application runs on Ruby >= 3.1, Rails 7.2.1, and SQLite 3.46.1 (gem version 2.0.4).

Setup

First you need to clone the repository to your local machine:

git clone [email protected]:fractaledmind/euruko-2024.git
cd euruko-2024

After cloning the repository, install the dependencies:

bundle install

I have built the repository to be usable out-of-the-box. It contains a seeded production database, precompiled assets, and a binscript to start the server in production mode. The only other things you will need besides the RubyGems dependencies are multiple different Ruby versions and the load testing tool oha.

Setup Ruby Versions

By default, this repository uses Ruby 3.1.6, which is the most recent point release on the 3.1 branch. As a part of the exploration of the performance impact of different Ruby versions on SQLite-backed Rails applications, we will be testing the following Ruby versions:

ruby-3.3.5
ruby-3.2.5
ruby-3.1.6

Please make sure you have each of these Ruby versions installed on your machine. If you are using rbenv, you can install them with commands like the following:

rbenv install 3.3.5

Or, if you are using asdf, you can install them like so:

asdf install ruby 3.3.5

If you manage Ruby versions some other way, I'm sure you know how to install new Ruby versions with your tool of choice.

Setup Load Testing

Load testing can be done using the oha CLI utility, which can be installed on MacOS via homebrew:

brew install oha

and on Windows via winget:

winget install hatoo.oha

or using their precompiled binaries on other platforms.

Load Testing

Throughout this workshop, we will be load testing the application to observe how our various changes impact the performance of the application. In order to perform the load testing, you will need to run the web server in the production environment. I have provided a binscript to make this easier. To start the production server, run the following command:

bin/serve

This simply a shortcut for the following command:

RAILS_ENV=production RELAX_SSL=true RAILS_LOG_LEVEL=warn WEB_CONCURRENCY=10 RAILS_MAX_THREADS=5 bin/rails server

The RELAX_SSL environment variable is necessary to allow you to use http://localhost. The RAILS_LOG_LEVEL is set to warn to reduce the amount of logging output. Set WEB_CONCURRENCY to the number of cores you have on your laptop. I am on an M1 Macbook Pro with 10 cores, and thus I set the value to 10. The RAILS_MAX_THREADS controls the number of threads per worker. I left it at the default of 5, but you can tweak it to see how it affects performance.

With your server running in one terminal window, you can use the load testing utility to test the app in another terminal window. Here is the shape of the command you will use to test the app:

oha -c N -z 10s -m POST http://localhost:3000/benchmarking/PATH

N is the number of concurrent requests that oha will make. I recommend running a large variety of different scenarios with different values of N. Personally, I scale up from 1 to 256 concurrent requests, doubling the number of concurrent requests each time. In general, when N matches your WEB_CONCURRENCY number, this is mostly likely the sweet spot for this app.

PATH can be any of the benchmarking paths defined in the app. The app has a few different paths that you can test. From the routes.rb file:

namespace :benchmarking do
  post "post_create"
  post "comment_create"
  post "post_destroy"
  post "comment_destroy"
  post "post_show"
  post "posts_index"
  post "user_show"
end

You can validate that the application is properly set up for load testing by serving the application in one terminal window/tab (via bin/serve) and then running the following curl command in another terminal window/tab:

curl -s -o /dev/null -w "%{http_code}" -X POST http://localhost:3000/benchmarking/posts_index

If this returns 200, then next ensure that you can run an oha command like the following:

oha -c 1 -z 1s -m POST http://localhost:3000/benchmarking/posts_index

If this runs successfully, then you are ready to begin the workshop.

Workshop

You will find the workshop instructions in the workshop/ directory. The workshop is broken down into a series of steps, each of which is contained in a separate markdown file. The workshop is designed to be self-guided, but I am available to help if you get stuck. Please feel free to reach out to me on Twitter at @fractaledmind if you have any questions.

The first step is to run some baseline load tests. Once you have completed that step, you can move on to the next step, which will be linked at the bottom of each step.