Definition

Backpressure is a technique to prevent system overload by signaling to upstream components to slow down when downstream is overwhelmed.

Core concept

In streaming or concurrent systems, if a consumer can’t keep up, it applies backpressure so producers send data slower or buffer. This avoids unchecked queues and resource exhaustion.

Use cases

Message brokers (Kafka has backpressure in some flows), streaming frameworks (Reactive Streams). In microservices, one service can return HTTP 503 or throttle signals to slow clients.

Trade-offs

Adds flow control complexity. If not designed well, backpressure can lead to cascading slowdowns.

Example

A web API might implement a rate-limit header or connection pool limits to apply backpressure.

References

Theory of reactive systems (no direct cite).