trace where Ruby objects come from with this handy bash 3 liner

command-line-only-objectspace-trace.sh

echo 'require "objspace"; ObjectSpace.trace_object_allocations_start; Kernel.send(:define_method, :sup) do |obj| ;   puts "#{ ObjectSpace.allocation_sourcefile(obj) }:#{ ObjectSpace.allocation_sourceline(obj) }"; end' > tmp/tmp-gemfile
cat Gemfile >> tmp/tmp-gemfile
cat tmp/tmp-gemfile > Gemfile

# $ bundle exec irb
# irb(main):001:0> require 'rails'
# => true
# irb(main):002:0> sup(Rails)
# /Users/richardschneeman/.gem/ruby/2.4.0/gems/railties-5.0.0.1/lib/rails/initializable.rb:3