Question

本书 Ruby 1.9＆2.0编程中给出了以下示例：

require 'irb'

trap "INT" do
  IRB.start
end

count = 0
loop do
  count += 1
  puts count
  puts "Value = #{@value}" if defined? @value
  sleep 1
end

不幸的是，如果我使用Ruby 2.5.1安装程序运行此代码，则会得到以下ThreadError（ run_irb.rb 是具有上面代码的文件的名称）：< / p>

    24: from run_irb.rb:8:in `<main>'
    23: from run_irb.rb:8:in `loop'
    22: from run_irb.rb:12:in `block in <main>'
    21: from run_irb.rb:12:in `sleep'
    20: from run_irb.rb:4:in `block in <main>'
    19: from /usr/lib/ruby/2.5.0/irb.rb:376:in `start'
    18: from /usr/lib/ruby/2.5.0/irb/init.rb:17:in `setup'
    17: from /usr/lib/ruby/2.5.0/irb/init.rb:112:in `init_config'
    16: from /usr/lib/ruby/2.5.0/irb/init.rb:112:in `new'
    15: from /usr/lib/ruby/2.5.0/irb/locale.rb:32:in `initialize'
    14: from /usr/lib/ruby/2.5.0/irb/locale.rb:108:in `load'
    13: from /usr/lib/ruby/2.5.0/irb/locale.rb:124:in `find'
    12: from /usr/lib/ruby/2.5.0/irb/locale.rb:145:in `search_file'
    11: from /usr/lib/ruby/2.5.0/irb/locale.rb:157:in `each_localized_path'
    10: from /usr/lib/ruby/2.5.0/irb/locale.rb:167:in `each_sublocale'
     9: from /usr/lib/ruby/2.5.0/irb/locale.rb:158:in `block in each_localized_path'
     8: from /usr/lib/ruby/2.5.0/irb/locale.rb:150:in `block in search_file'
     7: from /usr/lib/ruby/2.5.0/rubygems.rb:213:in `try_activate'
     6: from /usr/lib/ruby/2.5.0/rubygems/specification.rb:1063:in `find_by_path'
     5: from /usr/lib/ruby/2.5.0/rubygems/specification.rb:1063:in `find'
     4: from /usr/lib/ruby/2.5.0/rubygems/specification.rb:1063:in `each'
     3: from /usr/lib/ruby/2.5.0/rubygems/specification.rb:1064:in `block in find_by_path'
     2: from /usr/lib/ruby/2.5.0/rubygems/core_ext/kernel_require.rb:40:in `require'
     1: from /usr/lib/ruby/2.5.0/monitor.rb:185:in `mon_enter'
/usr/lib/ruby/2.5.0/monitor.rb:185:in `lock': can't be called from trap context (ThreadError)

是否有办法使用Ruby 2.5.1从trap上下文中运行irb？

Answer 1

Ruby 2.0不允许在信号处理程序中使用Mutex＃lock

根据红宝石语言中的bug 7917，这是“预期”行为。因此，您基本上已经找到了语言错误和书籍错误，因为作者没有在ruby 2.0中测试此示例（确认它可以在1.9中运行。）

另一种方法是使用异常/救援，并从这样的中断执行IRB会话：

require 'irb'

count = 0
loop do
  count += 1
  puts count
  puts "Value = #{@value}" if defined? @value
  sleep 1
rescue Interrupt => e
  IRB.start
  break
end

以上内容将正确捕获中断，并允许IRB会话开始。我确实注意到IRB.start不会为您提供本地执行上下文，因此您可能希望查看binding.irb，以便您启动这样一个更有用的调试会话：

$ ruby thread-test.rb
1
2
^C
[1] irb(main)>

From: /work/_scratch/thread-test/thread-test.rb @ line 11 :

     6:   puts count
     7:   puts "Value = #{@value}" if defined? @value
     8:   sleep 1
     9: rescue Interrupt => e
    10:   binding.irb
 => 11:   break
    12: end

[2] irb(main)> e
=> Interrupt
[3] irb(main)> count
=> 2

我发现了一些有关处理Signals, Traps, and Rescues和Graceful Shutdown的博客文章，可能会帮助您进一步解决问题。

Ruby：从陷阱上下文运行irb？

1 个答案: