Announcing a new iHeartRadio open source project Kanaloa. Kanaloa is a set of work dispatchers implemented using Akka actors. These dispatchers sit in front of your service and dispatch received work to them. They make your service more resilient through the following means:

  1. Auto scaling - it dynamically figures out the optimal number of concurrent requests your service can handle, and make sure that at any given time your service handles no more than that number of concurrent requests. This algorithm was also ported and contributed to Akka as Optimal Size Exploring Resizer (although with some caveats).

  2. Back pressure control - this control is Little’s law inspired. It rejects requests when estimated wait time of which exceeds a certain threshold.

  3. Circuit breaker - when error rate from your service goes above a certain threshold, kanaloa dispatcher stops all requests for a short period of time to give your service a chance to “cool down”.

  4. Real-time monitoring - a built-in statsD reporter allows you to monitor a set of critical metrics (throughput, failure rate, queue length, expected wait time, service process time, number of concurrent requests, etc) in real time. It also provides real-time insights into how kanaloa dispatchers are working. An example on Grafana:Dashboard