原來這個叫做 Delayed Queue，難怪之前用其他關鍵字都找不到什麼資料... (就不講其他關鍵字了 XD)
Traditionally, we have been using a Cassandra based queue recipe along with Zookeeper for distributed locks, since Cassandra is the de facto storage engine at Netflix.
但可以馬上想到不少問題，就如同 Netflix 提到的：
Using Cassandra for queue like data structure is a known anti-pattern, also using a global lock on queue while polling, limits the amount of concurrency on the consumer side as the lock ensures only one consumer can poll from the queue at a time.
所以就改放到 Netflix 另外開發的 Dynamite 上：
Dynomite, inspired by Dynamo whitepaper, is a thin, distributed dynamo layer for different storage engines and protocols. Currently these include Redis and Memcached. Dynomite supports multi-datacenter replication and is designed for high availability.
在設計上則是「保證會跑一次」，也就是有可能會有多次的情況，用 Dyno Queues 系統的人必需要考慮進去：
4. At-least-once delivery semantics
雖然整篇講的頗輕鬆，但實際看起來還是很厚重... 暫時還是不會用吧 :o