Chapter 5. Writing Applications that Scale
Imagine the checkout counter of a supermarket on a Saturday evening, the usual rush-hour time. It is common to see long queues of people waiting to check out with their purchases. What could a store manager do to reduce the rush and waiting time?
A typical manager would try a few approaches, including telling those manning the checkout counters to pick up their speed, and to try and redistribute people to different queues so that each queue roughly has the same waiting time. In other words, they would manage the current load with available resources by optimizing the performance of the existing resources.
However, if the store has existing counters that are not in operation—and enough people at hand to manage them—the manager could enable those counters, and move people to these new counters. In other words, they would add resources to the store to scale the operation.
Software systems, too, scale in a similar way. An existing...
