您在irb中运行了此代码，对吗？您收到的异常实际上不是由引发的
Redis.new。它是由
inspect方法引发的，irb调用该方法以向您显示刚刚键入的表达式的值。
只需查看堆栈跟踪（我缩短了使其清晰的路径）：
ruby-1.8.7-p330 :009 > Redis.new(:host => "google.com")Timeout::Error: time's up! from /.../SystemTimer-1.2.3/lib/system_timer/concurrent_timer_pool.rb:63:in `trigger_next_expired_timer_at' from /.../SystemTimer-1.2.3/lib/system_timer/concurrent_timer_pool.rb:68:in `trigger_next_expired_timer' from /.../SystemTimer-1.2.3/lib/system_timer.rb:85:in `install_ruby_sigalrm_handler' from /..../lib/ruby/1.8/monitor.rb:242:in `synchronize' from /.../SystemTimer-1.2.3/lib/system_timer.rb:83:in `install_ruby_sigalrm_handler' from /.../redis-2.2.2/lib/redis/connection/ruby.rb:26:in `call' from /.../redis-2.2.2/lib/redis/connection/ruby.rb:26:in `initialize' from /.../redis-2.2.2/lib/redis/connection/ruby.rb:26:in `new' from /.../redis-2.2.2/lib/redis/connection/ruby.rb:26:in `connect' from /.../SystemTimer-1.2.3/lib/system_timer.rb:60:in `timeout_after' from /.../redis-2.2.2/lib/redis/connection/ruby.rb:115:in `with_timeout' from /.../redis-2.2.2/lib/redis/connection/ruby.rb:25:in `connect' from /.../redis-2.2.2/lib/redis/client.rb:227:in `establish_connection' from /.../redis-2.2.2/lib/redis/client.rb:23:in `connect' from /.../redis-2.2.2/lib/redis/client.rb:247:in `ensure_connected' from /.../redis-2.2.2/lib/redis/client.rb:137:in `process'... 2 levels... from /.../redis-2.2.2/lib/redis/client.rb:46:in `call' from /.../redis-2.2.2/lib/redis.rb:90:in `info' from /..../lib/ruby/1.8/monitor.rb:242:in `synchronize' from /.../redis-2.2.2/lib/redis.rb:89:in `info' from /.../redis-2.2.2/lib/redis.rb:1075:in `inspect' from /..../lib/ruby/1.8/monitor.rb:242:in `synchronize' from /.../redis-2.2.2/lib/redis.rb:1074:in `inspect' from /..../lib/ruby/1.8/irb.rb:310:in `output_value' from /..../lib/ruby/1.8/irb.rb:159:in `eval_input' from /..../lib/ruby/1.8/irb.rb:271:in `signal_status' from /..../lib/ruby/1.8/irb.rb:155:in `eval_input' from /..../lib/ruby/1.8/irb.rb:154:in `eval_input' from /..../lib/ruby/1.8/irb.rb:71:in `start' from /..../lib/ruby/1.8/irb.rb:70:in `catch' from /..../lib/ruby/1.8/irb.rb:70:in `start' from /..../bin/irb:17
如您在上面看到的，该异常发生在
inspect而不是内部
Redis.new。当您调用
inspectRedis对象时，它实际上不仅仅是在打印其状态，而且还可以做很多事情。在这种情况下，
inspect尝试连接到服务器并在超时时引发异常。这对我来说似乎是一个非常糟糕的设计，也许我们应该向Redis
gem的维护者提交错误报告。
这导致了IRB中一些有趣的行为：
- 键入会
Redis.new(:host => "google.com")
导致异常，如上所示 - 输入
Redis.new(:host => "google.com"); 'hello'
结果为’=> "hello"
‘
如果要捕获此异常，请尝试
ensure_connected在begin / rescue / end块内调用。
