Assessment

This is a memory footprint assessment of all the possibilities to start the Rack server and the assets watch. I know this isn't a scientific approach, but it gives us the order of magnitude of the differences between the options.

Conclusions

Using Ruby and NPM as middlemen to execute other commands wastes memory.
- bundle exec hanami server and assets, npm exec
Foreman executes 3 Ruby processes.
Guard executes 2 Ruby and 1 UNIX processes.
The official way (as of v2.1.0.beta2) is hanami dev consumes the most memory: 227 Mb
There are less memory hungry solutions (57 Mb) that require other considerations: installing extra tools

Data

Config

Puma

# frozen_string_literal: true

max_threads_count = ENV.fetch("HANAMI_MAX_THREADS", 5)
min_threads_count = ENV.fetch("HANAMI_MIN_THREADS") { max_threads_count }
threads min_threads_count, max_threads_count

port        ENV.fetch("HANAMI_PORT", 2300)
environment ENV.fetch("HANAMI_ENV", "development")
workers     ENV.fetch("HANAMI_WEB_CONCURRENCY", 0)

if ENV.fetch("HANAMI_WEB_CONCURRENCY", 0) > 0
  on_worker_shutdown do
    Hanami.shutdown
  end
end

preload_app!

Procfile

web: bundle exec hanami server
assets: bundle exec hanami assets watch

Guardfile

# frozen_string_literal: true

group :server do
  guard "puma", port: ENV.fetch("HANAMI_PORT", 2300) do
    watch(%r{config/*})
    watch(%r{lib/*})
    watch(%r{app/[^/]+.rb})
    watch(%r{app/templates/.+..+..+})
    watch(%r{slices/.+/.+.rb})
    watch(%r{slices/.+/templates/.+..+..+})
  end
end

HTTP

Rackup [36.6Mb]

Server: 36.6 Mb

$ bundle exec rackup

Puma [37.3 Mb]

Server: 37.3 Mb

$ bundle exec puma

Hanami Server (no code reloading) [39.7 Mb]

Server: 39.7 Mb

$ bundle exec hanami server --no-code-reloading

Hanami Server (w/ code reloading, using Guard) [85.5 Mb]

Server: 34.4 Mb
Guard (main): 32 Mb
Guard (child): 19.1 Mb

Assets

Node Assets watch [17.5 Mb]

Node: 17.5 Mb

$ node_modules/hanami-assets/dist/hanami-assets.js --watch

NPM Assets watch [50.1 Mb]

NPM: 31.9 Mb
Node: 18.2 Mb

$ npm exec hanami-assets -- --watch

Dev

Foreman [185.6 Mb]

Foreman: 15.6 Mb
Foreman (web, Guard main): 19 Mb
Guard (Puma): 32.8 Mb
Foreman (assets): 36 Mb
Puma: 34 Mb
fsevent_watch: 1.1 Mb
Node: 17.1 Mb
NPM: 30 Mb

Hanami Dev (code reloading + assets watch) [227.3 Mb]

Hanami Dev: 34.4 Mb
Hanami Assets Watch: 35.7 Mb
Foreman: 16.1 Mb
Foreman (web, Guard main): 19.5 Mb
Foreman (assets): 35.7 Mb
Puma: 35.0 Mb
NPM: 31.7 Mb
NPM: 18.1 Mb
fsevent_watch: 1.1 Mb

bin/dev (shoreman + watchexec) [57.2 Mb]

Shoreman is a Foreman replacement. https://github.com/chrismytton/shoreman Watchexec is a Guard replacement. https://github.com/watchexec/watchexec

Puma: 36.5 Mb
Node: 18.0 Mb
watchexec: 2.7 Mb

bin/dev

#!/usr/bin/env sh
shoreman Procfile.dev

Procfile.dev

web: watchexec -w app -w config -w lib -w slices --exts rb,erb,haml,slim -r "bundle exec rackup -p 2300"
assets: node_modules/hanami-assets/dist/hanami-assets.js --watch

Notes for this option:

PRO: We save 170 Mb if compared with the current implementation of hanami dev
PRO: We can remove hanami-reloader, guard, and guard-puma as development deps.
CONS: We need to distribute shoreman. It isn't hard, it's a Bash script, we can vendor in Hanami.
CONS: We need users to install watchexec. It's distributed via all the common package managers.

jodosha/README.md