Thin LoadError: no such file to load thin_parser - ruby-on-rails-3

Question

I have installed thin and try to do thin start, which end up with this error
C:/Ruby192/lib/ruby/site_ruby/1.9.1/rubygems/custom_require.rb:36:in `require': no such file to load -- C:/Ruby192/lib/ruby/gems/1.9.1/gems/thin-1.2.8-x86-mingw32/lib/1.9/thin_parser (LoadError)
from C:/Ruby192/lib/ruby/site_ruby/1.9.1/rubygems/custom_require.rb:36:in `require'
from C:/Ruby192/lib/ruby/gems/1.9.1/gems/thin-1.2.8-x86-mingw32/lib/thin.rb:48:in `rescue in <top (required)>'
from C:/Ruby192/lib/ruby/gems/1.9.1/gems/thin-1.2.8-x86-mingw32/lib/thin.rb:43:in `<top (required)>'
from C:/Ruby192/lib/ruby/site_ruby/1.9.1/rubygems/custom_require.rb:36:in `require'
from C:/Ruby192/lib/ruby/site_ruby/1.9.1/rubygems/custom_require.rb:36:in `require'
from C:/Ruby192/lib/ruby/gems/1.9.1/gems/thin-1.2.8-x86-mingw32/bin/thin:5:in `<top (required)>'
from C:/Ruby192/bin/thin:19:in `load'
from C:/Ruby192/bin/thin:19:in `<main>'
Can someone help me out please, thanks in advance

Answer 1

the output denotes a directory called 1.9 i.e.
<ruby_install_dir>/lib/ruby/gems/1.9.1/gems/thin-1.2.8-x86-mingw32/lib/1.9/
Note: My thin version is 1.2.10. In the following i will use the path as it appears on my system.
For some reason the thin gem doesn't come with this directory. But a file called thin_parser.so resides in the parent directory <ruby_install_dir>/lib/ruby/gems/1.9.1/gems/thin-1.2.10/lib/
So my first solution was to create a directory 1.9 and copy the file thin_parser.so to it.
Now thin start works for me.
Alternatively you can edit the file <ruby_install_dir>/lib/ruby/gems/1.9.1/gems/thin-1.2.10/lib/thin.rb and change
if Thin.win?
# Select proper binary under Windows
major_ruby_version = RUBY_VERSION[/^(\d+\.\d+)/]
require "#{Thin::ROOT}/#{major_ruby_version}/thin_parser"
else
require "#{Thin::ROOT}/thin_parser"
end
to
if Thin.win?
# Select proper binary under Windows
major_ruby_version = RUBY_VERSION[/^(\d+\.\d+)/]
require "#{Thin::ROOT}/thin_parser"
else
require "#{Thin::ROOT}/thin_parser"
end
or even simpler
require "#{Thin::ROOT}/thin_parser"
I'm not sure what workaround is the better one, since i don't know what else files thin expects in the not existing directory. I don't know either where the Thin.win? fork becomes important.
I decided in favor of the first solution. But both ways fixed the Problem for me.
Best regards,
Tim

Answer 2

I ran into this same error when running rake db:migrate (I suspect thin start would have given me the same error.)
I'm running on Amazon Linux (rpm based, so similar to CentOS and Redhat). I had previously installed thin as root (gem install thin). Although it may be irrelevant to your situation, just for completeness, I had also installed eventmachine using:
gem install eventmachine --platform=ruby
Here is the error I got:
% rake db:migrate
rake aborted!
LoadError: cannot load such file -- thin_parser
/home/rails/.gem/ruby/1.9.1/gems/activesupport-3.2.8/lib/active_support/dependencies.rb:251:in `require'
etc. etc.
Based on the above information, I ran rake under strace and discovered that it was looking for thin_parser.so in the wrong place. I was able to fix the problem by installing this symbolic link (I did this as root since I installed thin as root). Obviously, adjust the path to where your version of thin is installed:
cd /usr/local/share/gems1.9/gems/thin-1.6.3/lib
ln -s ../ext/thin_parser/thin_parser.so .
Poof! That fixed it for me.