IIRC, Celery uses token bucket algorithm for rate limiting. SHARQ uses the leaky bucket algorithm (http://en.wikipedia.org/wiki/Leaky_bucket#The_Leaky_Bucket_Al

IIRC, Celery uses token bucket algorithm for rate limiting. SHARQ uses the leaky bucket algorithm (http://en.wikipedia.org/wiki/Leaky_bucket#The_Leaky_Bucket_Algorithm_as_a_Queue http://en.wikipedia.org/wiki/Leaky_bucket#The_Leaky_Bucket_A...). The advantage of leaky bucket is that, it enforces a constant flow of jobs out of SHARQ regardless of the spike in enqueue rate. Even though SHARQ uses Redis, it has been designed in a way to support at-least-once delivery. If you see the getting started section (http://sharq.io/docs/gettingstarted.html http://sharq.io/docs/gettingstarted.html), there is a Finish API which would acknowledge every job dequeued. SHARQ ensures that a job will be requeued back into the queue if it does not receive a Finish request.