The win32-thread library is and experimental library for native threads on MS Windows. Note that this library is largely a proof of concept library and should not be used in production systems because it is likely to crash the Ruby interpreter. Users of Ruby 1.9.x should not need this library since those versions use native threads by default.
Gemfile gem 'win32-thread', '~> 0.0.3'
install gem install win32-thread