mongodb/mongo-ruby-driver — pull request #551 by jeromegn (2014-11-26 19:01:56+00:00)
Title: Clean up Mongo::Server::Monitor on Mongo::Server#disconnect!

While attempting to disconnect a Mongo::Client, I noticed even after running `client.cluster.servers.each(&:disconnect!)` that there was still `ismaster: 1` commands being executed.

I figured the Mongo::Server::Monitor instance associated with a Mongo::Server would need to be "stopped" by killing the Thread it created.