我在 Rails 应用程序中包含了这个简单的 Rack 中间件：
class Hello
def initialize(app)
@app = app
end
def call(env)
[200, {"Content-Type" => "text/html"}, "Hello"]
end
end
将其插入 environment.rb 中：
...
Dir.glob("#{RAILS_ROOT}/lib/rack_middleware/*.rb").each do |file|
require file
end
Rails::Initializer.run do |config|
config.middleware.use Hello
...
我正在使用 Rails 2.3.5、Webrick 1.3.1、ruby 1.8.7
当应用程序在生产模式下启动时，一切都按预期工作 - 每个请求都被 Hello 中间件拦截，并返回“Hello”。但是，在开发模式下运行时，第一个请求返回“Hello”，但下一个请求挂起。
在 webrick 处于挂起状态时中断它会产生以下结果：
^C[2010-03-24 14:31:39] INFO going to shutdown ...
deadlock 0xb6efbbc0: sleep:- - /usr/lib/ruby/gems/1.8/gems/actionpack-2.3.5/lib/action_controller/reloader.rb:31
deadlock 0xb7d1b1b0: sleep:J(0xb6efbbc0) (main) - /usr/lib/ruby/1.8/webrick/server.rb:113
Exiting
/usr/lib/ruby/1.8/webrick/server.rb:113:in `join': Thread(0xb7d1b1b0): deadlock (fatal)
from /usr/lib/ruby/1.8/webrick/server.rb:113:in `start'
from /usr/lib/ruby/1.8/webrick/server.rb:113:in `each'
from /usr/lib/ruby/1.8/webrick/server.rb:113:in `start'
from /usr/lib/ruby/1.8/webrick/server.rb:23:in `start'
from /usr/lib/ruby/1.8/webrick/server.rb:82:in `start'
from /usr/lib/ruby/gems/1.8/gems/rack-1.0.1/lib/rack/handler/webrick.rb:14:in `run'
from /usr/lib/ruby/gems/1.8/gems/rails-2.3.5/lib/commands/server.rb:111
from /usr/local/lib/site_ruby/1.8/rubygems/custom_require.rb:31:in `gem_original_require'
from /usr/local/lib/site_ruby/1.8/rubygems/custom_require.rb:31:in `require'
from script/server:3
与开发模式下的类重新加载器有关。异常中还提到了死锁。
有什么想法可能导致这种情况吗？关于调试此问题的最佳方法有什么建议吗？
更新
$ script/console
Loading development environment (Rails 2.3.5)
>> app.get '/'
=> 200
>> app.get '/'
ThreadError: stopping only thread
note: use sleep to stop forever
from /usr/lib/ruby/gems/1.8/gems/actionpack-2.3.5/lib/action_controller/reloader.rb:31:in `lock'
from /usr/lib/ruby/gems/1.8/gems/actionpack-2.3.5/lib/action_controller/reloader.rb:31:in `run'
from /usr/lib/ruby/gems/1.8/gems/actionpack-2.3.5/lib/action_controller/dispatcher.rb:108:in `call'
from /usr/lib/ruby/gems/1.8/gems/rack-1.0.1/lib/rack/lint.rb:47:in `_call'
from /usr/lib/ruby/gems/1.8/gems/rack-1.0.1/lib/rack/lint.rb:35:in `call'
from /usr/lib/ruby/gems/1.8/gems/actionpack-2.3.5/lib/action_controller/integration.rb:316:in `process'
from /usr/lib/ruby/gems/1.8/gems/actionpack-2.3.5/lib/action_controller/integration.rb:197:in `get'
from (irb):2
看起来它可能与这个问题有关：