Prefer require_relative

[marcandre]

There are over 300 calls to require that could be more efficient with require_relative. If I'm not mistaken, current rubygems supports only Ruby 2.2+, so this is a free speed gain.

[deivid-rodriguez]

Hi @marcandre, thanks for this! This was proposed in #2373, but rejected by @hsbt because he wanted a benchmark to prove the speed gain.

I tried to write one so that he will accept this. You can pass an integer argument to the script that sets the LOAD_PATH size. The higher the argument, the greater the speed gain.

require "fileutils"
require "benchmark/ips"

def load_path(n)
  $LOAD_PATH.replace([])

  (1..n.to_i).map do |dir|
    $LOAD_PATH << dir.to_s
  end

  Dir.mkdir(n)
  FileUtils.touch("#{n}/a.rb")
end

n = ARGV[0]

load_path(n)

Benchmark.ips do |x|
  x.report("require with LOAD_PATH of size #{n}:") { require "a" }
  x.report("require_relative with LOAD_PATH of size #{n}:") { require_relative "#{n}/a" }
  x.compare!
end

File.delete("#{n}/a.rb")
Dir.rmdir(n)

[marcandre]

One thing is for sure, require_relative can only be faster than require 😆!

It's also better styling by being more explicit: makes requires of other gems stand out compared to files of rubygems itself.

[deivid-rodriguez]

Absolutely, I would enable this just for style! But both of the times this was proposed performance was mentioned so I want to make sure it's accepted anyways :)

[MSP-Greg]

@deivid-rodriguez @marcandre

Thanks for this, and the benchmark. Working with Windows CI as much as I do, I've seen a wide variance In test times. Probably partly due to shared i/o on a drive. This will certainly help...

[amatsuda]

@marcandre I once did the same thing for Rails rails/rails#29638,
then the users hit this bug rails/rails#29638 (comment),
and so we made these fixes in Ruby 2.5 a year ago:
ruby/ruby@5754f15
ruby/ruby@b6d3927

I suppose the users will face the same problem where having rubygems with your patch installed under a symlinked path. We need to wait until rubygems is totally dropping Ruby < 2.5 support.

[deivid-rodriguez]

Wow, @amatsuda, thanks. I was completely unaware of these issues. Let's wait then, yeah.

[MSP-Greg]

I'm not familiar with rvm, but I'm wondering about use cases where this would be an issue.

RG Is similar to a std-lib, in that normal installs or updates are always within the lib folder. Gems (Rails) are different.

I haven't been in the bundler code for quite a while, but I rarely see code loading parts of RG. A Gem class method or maybe some of the command files...

There maybe issues with some CI scenarios.

[marcandre]

Oh, I see. So any path that might be required (from another gem/app) should not be also require_relative until Ruby 2.5+.

Since it's hard to know for which files this might be the case, probably best to wait then 😿