Slow require 'concurrent' on windows

[Largo]

Hi!
So I'm on the hunt for the reason why my app needs seconds to start instead of miliseconds. I'm using TZInfo in my app which depends on concurrent-ruby. I'm not sure if anything can be done about it, as the issue might lie with ruby on windows but maybe it can be improved? I assume this also affects rails on windows startup.

require 'benchmark'
 puts Benchmark.measure {
     require   'concurrent'
}

Windows benchmark on an intel core i9 laptop:
0.047000 0.734000 0.781000 ( 2.150554)

Linux benchmark on a simple cloud VPS:
0.043045 0.003789 0.046834 ( 0.050957)

2.10 seconds vs 0.05 seconds

Thanks for your hard work!

* Operating system:                 win
* Ruby implementation:             Ruby 3.1.2
* `concurrent-ruby` version:       1.1.10
* `concurrent-ruby-ext` installed: no
* `concurrent-ruby-edge` used:      no

[chrisseaton]

Can you profile it for me?

I'm sorry I'm not going to be able to help with anything Windows-specific - I just don't know anything about it.

[Largo]

It is faster today, probably because of a cache, I've also checked the code and could only find one windows specific part, which doesn't seem to be an issue.
It might just be "require" itself , which is known to be slower on windows.

require 'ruby-prof'

result = RubyProf.profile do
 require 'concurrent'
end

printer = RubyProf::FlatPrinter.new(result)
printer.print(File.open("ruby_prof_example_api1_profile.txt", "w+"))

Measure Mode: wall_time
Thread ID: 80
Fiber ID: 60
Total: 0.581108
Sort by: self_time

 %self      total      self      wait     child     calls  name                           location
 68.93      0.567     0.401     0.000     0.167      295  *Kernel#gem_original_require    
 17.81      0.104     0.104     0.000     0.000     3629   <Class::File>#file?            
  2.66      0.016     0.015     0.000     0.000        6  *Kernel#require_relative        
  2.15      0.013     0.013     0.000     0.000      105   <Class::File>#exist?           
  1.38      0.121     0.008     0.000     0.113     2281  *Array#any?                     
  0.68      0.004     0.004     0.000     0.000     1323   <Class::File>#join             
  0.50      0.003     0.003     0.000     0.000     3626   String#+                       
  0.44      0.003     0.003     0.000     0.000       75   Module#class_eval              
  0.36      0.147     0.002     0.000     0.145     1060   Gem::BasicSpecification#contains_requirable_file? C:/Ruby31-x64/lib/ruby/3.1.0/rubygems/basic_specification.rb:72
  0.35      0.128     0.002     0.000     0.126     1060   Gem::BasicSpecification#have_file? C:/Ruby31-x64/lib/ruby/3.1.0/rubygems/basic_specification.rb:332
  0.35      0.581     0.002     0.000     0.579      294  *Kernel#require                 <internal:C:/Ruby31-x64/lib/ruby/3.1.0/rubygems/core_ext/kernel_require.rb>:36
  0.35      0.002     0.002     0.000     0.000     4119   Gem::StubSpecification#data    C:/Ruby31-x64/lib/ruby/3.1.0/rubygems/stub_specification.rb:108
  0.29      0.003     0.002     0.000     0.002     1975   Gem::StubSpecification#extensions C:/Ruby31-x64/lib/ruby/3.1.0/rubygems/stub_specification.rb:168
  0.25      0.016     0.001     0.000     0.015     1060   Gem::StubSpecification#missing_extensions? C:/Ruby31-x64/lib/ruby/3.1.0/rubygems/stub_specification.rb:143
  0.24      0.153     0.001     0.000     0.152       63  *Array#each                     
  0.24      0.001     0.001     0.000     0.000     2151   Kernel#tap                     <internal:kernel>:89
  0.23      0.004     0.001     0.000     0.002     1062   Gem::BasicSpecification#have_extensions? C:/Ruby31-x64/lib/ruby/3.1.0/rubygems/basic_specification.rb:330
  0.21      0.001     0.001     0.000     0.000        3   File#flock                     
  0.13      0.002     0.001     0.000     0.001     1060   Gem::StubSpecification#raw_require_paths C:/Ruby31-x64/lib/ruby/3.1.0/rubygems/stub_specification.rb:139
  0.13      0.002     0.001     0.000     0.001     1068   Gem::StubSpecification#full_name C:/Ruby31-x64/lib/ruby/3.1.0/rubygems/stub_specification.rb:179
  0.10      0.001     0.001     0.000     0.000     1975   Gem::StubSpecification::StubLine#extensions 
  0.10      0.002     0.001     0.000     0.001        3   Kernel#eval                    
  0.10      0.001     0.001     0.000     0.000     1065   <Module::Gem>#suffixes         C:/Ruby31-x64/lib/ruby/3.1.0/rubygems.rb:944
  0.10      0.001     0.001     0.000     0.000      238   IO#set_encoding                
  0.08      0.000     0.000     0.000     0.000     2011   Array#empty?                   
  0.07      0.000     0.000     0.000     0.000     1060   Gem::StubSpecification#default_gem? C:/Ruby31-x64/lib/ruby/3.1.0/rubygems/stub_specification.rb:93
  0.07      0.000     0.000     0.000     0.000      942   Kernel#respond_to?             
  0.06      0.001     0.000     0.000     0.000      294   <Module::Gem>#find_unresolved_default_spec C:/Ruby31-x64/lib/ruby/3.1.0/rubygems.rb:1219
  0.06      0.000     0.000     0.000     0.000        3   IO#read                        
  0.05      0.000     0.000     0.000     0.000     1088   BasicObject#!                  
  0.05      0.000     0.000     0.000     0.000     1068   Gem::StubSpecification#gems_dir 
  0.05      0.000     0.000     0.000     0.000      411   Hash#[]                        
  0.05      0.000     0.000     0.000     0.000     1384   Module#method_added            
  0.05      0.000     0.000     0.000     0.000     1060   Gem::StubSpecification::StubLine#require_paths 
  0.04      0.000     0.000     0.000     0.000     1068   Gem::StubSpecification::StubLine#full_name 
  0.04      0.000     0.000     0.000     0.000       22   Module#attr_reader             
  0.03      0.000     0.000     0.000     0.000       20   Gem::Version#<=>               C:/Ruby31-x64/lib/ruby/3.1.0/rubygems/version.rb:347

[chrisseaton]

The top two make it seem like an IO issue? Are you one some kind of strange machine, or a virtualised machine?

This isn't likely to be a Concurrent Ruby issue, so I'm closing unless there is evidence otherwise. I'm happy to keep engaging with you here to try to help as best I can though.