mongo db中的tailable游标超时

我正在尝试在ruby中创建一个oplog观察器。 到目前为止，我已经在下面提出了一个小脚本。

require 'rubygems' require 'mongo' db = Mongo::Connection.new("localhost", 5151).db("local") coll = db.collection('oplog.$main') loop do cursor = Mongo::Cursor.new(coll, :tailable => true) while not cursor.closed? if doc = cursor.next_document puts doc else sleep 1 end end end 

这个问题是，在5或6秒之后它吐出大量数据时会超时并且我得到一个错误

 C:/RailsInstaller/Ruby1.8.7/lib/ruby/gems/1.8/gems/mongo-1.4.0/lib/../lib/mongo/connection.rb :807:in `check_response_flags': Query response returned CURSOR_NOT_FOUND. Either an invalid c ursor was specified, or the cursor may have timed out on the server. (Mongo::OperationFailure ) from C:/RailsInstaller/Ruby1.8.7/lib/ruby/gems/1.8/gems/mongo-1.4.0/lib/../lib/mongo/ connection.rb:800:in `receive_response_header' from C:/RailsInstaller/Ruby1.8.7/lib/ruby/gems/1.8/gems/mongo-1.4.0/lib/../lib/mongo/ connection.rb:768:in `receive' from C:/RailsInstaller/Ruby1.8.7/lib/ruby/gems/1.8/gems/mongo-1.4.0/lib/../lib/mongo/ connection.rb:493:in `receive_message' from C:/RailsInstaller/Ruby1.8.7/lib/ruby/gems/1.8/gems/mongo-1.4.0/lib/../lib/mongo/ connection.rb:491:in `synchronize' from C:/RailsInstaller/Ruby1.8.7/lib/ruby/gems/1.8/gems/mongo-1.4.0/lib/../lib/mongo/ connection.rb:491:in `receive_message' from C:/RailsInstaller/Ruby1.8.7/lib/ruby/gems/1.8/gems/mongo-1.4.0/lib/../lib/mongo/ cursor.rb:494:in `send_get_more' from C:/RailsInstaller/Ruby1.8.7/lib/ruby/gems/1.8/gems/mongo-1.4.0/lib/../lib/mongo/ cursor.rb:456:in `refresh' from C:/RailsInstaller/Ruby1.8.7/lib/ruby/gems/1.8/gems/mongo-1.4.0/lib/../lib/mongo/ cursor.rb:124:in `next_document' from n.rb:7 from n.rb:6:in `loop' from n.rb:6 

我不明白的是，当我能够看到实际数据时，它怎么会突然说光标找不到。 我对ruby很新，我必须采取的任何方向的想法对我都有用。

Answer 1

解决方案是我需要一个exception处理机制来捕获当游标在每秒写入次数较多的相对较小的oplog中读取最后一个文档时引发的exception。 由于游标到达oplog的末尾，因此会抛出一个没有更多记录的exception。

 require 'rubygems' require 'mongo' db = Mongo::Connection.new("localhost",5151).db("local") coll = db.collection('oplog.$main') loop do cursor = Mongo::Cursor.new(coll, :timeout => false, :tailable => true) while not cursor.closed? begin if doc = cursor.next_document puts "Timestamp" puts doc["ts"] puts "Record" puts doc["o"] puts "Affected Collection" puts doc["ns"] end rescue puts "" break end end end 

现在这可以在处理exception时起作用。 感谢mongodb用户谷歌小组向我指出这一点。