当我尝试执行 rake db:migrate 时出现此错误。相当令人沮丧。我已经安装了 perftools 2.0，但似乎没有帮助。
这是完整的跟踪：
dn51vdfn:rails jasonvdm$ rake db:migrate --trace
** Invoke db:migrate (first_time)
** Invoke environment (first_time)
** Execute environment
rake aborted!
dlopen(/Users/jasonvdm/.rvm/gems/ruby-1.9.3-p194@wheelz/gems/perftools.rb-0.5.6/lib/perftools.bundle, 9): Symbol not found: _ruby_current_thread
Referenced from: /Users/jasonvdm/.rvm/gems/ruby-1.9.3-p194@wheelz/gems/perftools.rb-0.5.6/lib/perftools.bundle
Expected in: flat namespace
in /Users/jasonvdm/.rvm/gems/ruby-1.9.3-p194@wheelz/gems/perftools.rb-0.5.6/lib/perftools.bundle - /Users/jasonvdm/.rvm/gems/ruby-1.9.3-p194@wheelz/gems/perftools.rb-0.5.6/lib/perftools.bundle
/Users/jasonvdm/.rvm/gems/ruby-1.9.3-p194@wheelz/gems/activesupport-3.1.3/lib/active_support/dependencies.rb:240:in `require'
/Users/jasonvdm/.rvm/gems/ruby-1.9.3-p194@wheelz/gems/activesupport-3.1.3/lib/active_support/dependencies.rb:240:in `block in require'
/Users/jasonvdm/.rvm/gems/ruby-1.9.3-p194@wheelz/gems/activesupport-3.1.3/lib/active_support/dependencies.rb:223:in `block in load_dependency'
/Users/jasonvdm/.rvm/gems/ruby-1.9.3-p194@wheelz/gems/activesupport-3.1.3/lib/active_support/dependencies.rb:640:in `new_constants_in'
/Users/jasonvdm/.rvm/gems/ruby-1.9.3-p194@wheelz/gems/activesupport-3.1.3/lib/active_support/dependencies.rb:223:in `load_dependency'
/Users/jasonvdm/.rvm/gems/ruby-1.9.3-p194@wheelz/gems/activesupport-3.1.3/lib/active_support/dependencies.rb:240:in `require'
/Users/jasonvdm/.rvm/gems/ruby-1.9.3-p194@wheelz/gems/rack-perftools_profiler-0.5.0/lib/rack/perftools_profiler/profiler.rb:43:in `initialize'
/Users/jasonvdm/.rvm/gems/ruby-1.9.3-p194@wheelz/gems/rack-perftools_profiler-0.5.0/lib/rack/perftools_profiler/profiler_middleware.rb:20:in `new'
/Users/jasonvdm/.rvm/gems/ruby-1.9.3-p194@wheelz/gems/rack-perftools_profiler-0.5.0/lib/rack/perftools_profiler/profiler_middleware.rb:20:in `initialize'
/Users/jasonvdm/.rvm/gems/ruby-1.9.3-p194@wheelz/gems/rack-perftools_profiler-0.5.0/lib/rack/perftools_profiler.rb:20:in `new'
/Users/jasonvdm/.rvm/gems/ruby-1.9.3-p194@wheelz/gems/rack-perftools_profiler-0.5.0/lib/rack/perftools_profiler.rb:20:in `new'
/Users/jasonvdm/.rvm/gems/ruby-1.9.3-p194@wheelz/gems/actionpack-3.1.3/lib/action_dispatch/middleware/stack.rb:43:in `build'
/Users/jasonvdm/.rvm/gems/ruby-1.9.3-p194@wheelz/gems/actionpack-3.1.3/lib/action_dispatch/middleware/stack.rb:112:in `block in build'
/Users/jasonvdm/.rvm/gems/ruby-1.9.3-p194@wheelz/gems/actionpack-3.1.3/lib/action_dispatch/middleware/stack.rb:112:in `each'
/Users/jasonvdm/.rvm/gems/ruby-1.9.3-p194@wheelz/gems/actionpack-3.1.3/lib/action_dispatch/middleware/stack.rb:112:in `inject'
/Users/jasonvdm/.rvm/gems/ruby-1.9.3-p194@wheelz/gems/actionpack-3.1.3/lib/action_dispatch/middleware/stack.rb:112:in `build'
/Users/jasonvdm/.rvm/gems/ruby-1.9.3-p194@wheelz/gems/railties-3.1.3/lib/rails/engine.rb:447:in `app'
/Users/jasonvdm/.rvm/gems/ruby-1.9.3-p194@wheelz/gems/railties-3.1.3/lib/rails/application/finisher.rb:37:in `block in <module:Finisher>'
Tasks: TOP => db:migrate => environment
帮助？我正在使用 Ruby 1.9.3-p194