One of best: Twitter’s message queue tool Kestrel
Good is not enough!
If you are an active Twitter user, you probably experienced the fail of Tweet update very often. But from time to time, such fail is less than before.
This progress is attributed to the new Message queue tool Kestrel, which is done by Robey Pointer. Kestrel is implement by Scala, which is boasted as one of best language for scale, typing.
The fundamental of Kestrel is very similar to starling, also a Message queue tool implemented by Ruby. It is said the Ruby garbage collection caused the problems of starling. As such, starling is being replaced by Kestrel in Twitter.