Queueing theory originated in 1909 with a paper written by a mathematician named Agner Krarup Erlang.
- He accurately estimated the probability that a call would be blocked at different capacity utilization levels.
It can provide essential insights to product developers because there're similar problems of unpredictable work arrival time and unpredictable task durations.
- Queue: the waiting work.
- Server: the resource performing the work, whose time to complete the work may be unpredictable.
- Arrival Process: the pattern with which work arrives, which is usually unpredictable.
- Service Process: the process in which the server accomplishes the work.
- Queueing discipline: how queue handles the waiting work.
Kendall notation: queue.