Backpressure

Backpressure is a very useful concept in the field of distributed systems. It is essentially a resistance to the desired flow of data through a system. This resistance can manifest in different ways, such as increased latency of requests or failed requests.

Backpressure can also be implicit or explicit.

Implicit backpressure

Implicit backpressure arises in a system that is overloaded by a traffic surge and becomes extremely slow.

Explicit backpressure

A system that rejects some requests during a traffic surge to maintain a good quality service essentially exerts explicit backpressure to its clients.

Note: Most of the techniques used to contain failure reflect how applications exert backpressure and how their clients handle backpressure.