刚学 ruby 不久，部署一个项目，其实这不是我的项目，我把 gem 给升级了，然后用 thin start -C rails.yml 去启动，然后就报错了， /home/rails/shared/bundle/ruby/1.9.1/gems/thin-1.5.1/lib/thin/runner.rb:143:in `parse!': invalid option: --threadpool-size=20 (OptionParser::InvalidOption)

from /home/rails/shared/bundle/ruby/1.9.1/gems/thin-1.5.1/lib/thin/runner.rb:48:in `initialize'

from /home/rails/shared/bundle/ruby/1.9.1/gems/thin-1.5.1/bin/thin:6:in `new'

from /home/rails/shared/bundle/ruby/1.9.1/gems/thin-1.5.1/bin/thin:6:in `'

from /usr/local/rvm/gems/ruby-1.9.3-p327/bin/thin:19:in `load'

from /usr/local/rvm/gems/ruby-1.9.3-p327/bin/thin:19:in `'

from /usr/local/rvm/gems/ruby-1.9.3-p327/bin/ruby_noexec_wrapper:14:in `eval'

from /usr/local/rvm/gems/ruby-1.9.3-p327/bin/ruby_noexec_wrapper:14:in `'

报了这个错误。这个是不是我升级 gem 时造成的啊？那我该怎么解决呢？