我对 Ruby 完全陌生，所以我的问题可能有一个非常简单的答案。但是，我在stackoverflow上找不到答案。我有以下非常简单的 Sinatra 应用程序：
# myapp.rb
require 'rubygems'
require 'sinatra'
require 'json'
range=(199..2000).step(1)
set :port, 8888
get '/hostname' do
content_type :json
return range.next.to_json
end
西纳特拉开始：
ruby testsinatra.rb
== Sinatra/1.0 has taken the stage on 8888 for development with backup from WEBrick
[2014-09-11 08:43:18] INFO WEBrick 1.3.1
[2014-09-11 08:43:18] INFO ruby 1.8.7 (2011-06-30) [x86_64-linux]
[2014-09-11 08:43:18] INFO WEBrick::HTTPServer#start: pid=8215 port=8888
并提供第一个请求：
curl -ks http://localhost:8888/hostname
199
但在第二个请求中失败并出现错误：
RuntimeError - 跨线程调用的延续：
/usr/lib/ruby/1.8/generator.rb:131:in `call'
/usr/lib/ruby/1.8/generator.rb:131:in `next'
/usr/lib/ruby/1.8/generator.rb:189:in `next'
testsinatra.rb:30:in `GET /hostname'
/usr/lib/ruby/gems/1.8/gems/sinatra-1.0/lib/sinatra/base.rb:863:in `call'
/usr/lib/ruby/gems/1.8/gems/sinatra-1.0/lib/sinatra/base.rb:863:in `route'
/usr/lib/ruby/gems/1.8/gems/sinatra-1.0/lib/sinatra/base.rb:521:in `instance_eval'
/usr/lib/ruby/gems/1.8/gems/sinatra-1.0/lib/sinatra/base.rb:521:in `route_eval'
/usr/lib/ruby/gems/1.8/gems/sinatra-1.0/lib/sinatra/base.rb:500:in `route!'
/usr/lib/ruby/gems/1.8/gems/sinatra-1.0/lib/sinatra/base.rb:497:in `catch'
/usr/lib/ruby/gems/1.8/gems/sinatra-1.0/lib/sinatra/base.rb:497:in `route!'
/usr/lib/ruby/gems/1.8/gems/sinatra-1.0/lib/sinatra/base.rb:476:in `each'
/usr/lib/ruby/gems/1.8/gems/sinatra-1.0/lib/sinatra/base.rb:476:in `route!'
/usr/lib/ruby/gems/1.8/gems/sinatra-1.0/lib/sinatra/base.rb:601:in `dispatch!'
/usr/lib/ruby/gems/1.8/gems/sinatra-1.0/lib/sinatra/base.rb:411:in `call!'
/usr/lib/ruby/gems/1.8/gems/sinatra-1.0/lib/sinatra/base.rb:566:in `instance_eval'
/usr/lib/ruby/gems/1.8/gems/sinatra-1.0/lib/sinatra/base.rb:566:in `invoke'
/usr/lib/ruby/gems/1.8/gems/sinatra-1.0/lib/sinatra/base.rb:566:in `catch'
/usr/lib/ruby/gems/1.8/gems/sinatra-1.0/lib/sinatra/base.rb:566:in `invoke'
/usr/lib/ruby/gems/1.8/gems/sinatra-1.0/lib/sinatra/base.rb:411:in `call!'
/usr/lib/ruby/gems/1.8/gems/sinatra-1.0/lib/sinatra/base.rb:399:in `call'
/usr/lib/ruby/gems/1.8/gems/rack-1.5.2/lib/rack/showexceptions.rb:24:in `call'
/usr/lib/ruby/gems/1.8/gems/rack-1.5.2/lib/rack/methodoverride.rb:21:in `call'
/usr/lib/ruby/gems/1.8/gems/rack-1.5.2/lib/rack/commonlogger.rb:33:in `call'
/usr/lib/ruby/gems/1.8/gems/sinatra-1.0/lib/sinatra/base.rb:979:in `call'
/usr/lib/ruby/gems/1.8/gems/sinatra-1.0/lib/sinatra/base.rb:1003:in `synchronize'
/usr/lib/ruby/gems/1.8/gems/sinatra-1.0/lib/sinatra/base.rb:1003:in `synchronize'
/usr/lib/ruby/gems/1.8/gems/sinatra-1.0/lib/sinatra/base.rb:979:in `call'
/usr/lib/ruby/gems/1.8/gems/rack-1.5.2/lib/rack/handler/webrick.rb:60:in `service'
/usr/lib/ruby/1.8/webrick/httpserver.rb:104:in `service'
/usr/lib/ruby/1.8/webrick/httpserver.rb:65:in `run'
/usr/lib/ruby/1.8/webrick/server.rb:173:in `start_thread'
/usr/lib/ruby/1.8/webrick/server.rb:162:in `start'
/usr/lib/ruby/1.8/webrick/server.rb:162:in `start_thread'
/usr/lib/ruby/1.8/webrick/server.rb:95:in `start'
/usr/lib/ruby/1.8/webrick/server.rb:92:in `each'
/usr/lib/ruby/1.8/webrick/server.rb:92:in `start'
/usr/lib/ruby/1.8/webrick/server.rb:23:in `start'
/usr/lib/ruby/1.8/webrick/server.rb:82:in `start'
/usr/lib/ruby/gems/1.8/gems/rack-1.5.2/lib/rack/handler/webrick.rb:14:in `run'
/usr/lib/ruby/gems/1.8/gems/sinatra-1.0/lib/sinatra/base.rb:946:in `run!'
/usr/lib/ruby/gems/1.8/gems/sinatra-1.0/lib/sinatra/main.rb:25
testsinatra.rb:27
显然，我缺少一些基本的东西。请指教。