DelayRequest

DelayRequest is a control message or directive used in distributed systems and message-passing architectures to request the postponement of request processing for a defined time interval. It is commonly employed to implement backpressure, mitigate burst traffic, and coordinate load shedding or maintenance windows across services.

A typical DelayRequest specifies a delay duration, a scope (which requests or resources are affected), an identifier to correlate with a prior operation, and optional metadata such as a reason and a deadline. Implementations may encode the instruction in the protocol header, a message broker payload, or as a quality-of-service annotation.

On receipt, the target should refrain from starting new work for the covered scope until the delay expires. In-flight or queued requests may be buffered, deprioritized, retried later, or dropped according to policy. The mechanism relies on synchronized clocks or a centralized scheduler to ensure consistent wake-up times.

DelayRequests are used in API gateways, service meshes, data replication, and event streams to moderate load during traffic spikes, coordinate maintenance, or align processing windows across distributed components. They can be combined with other flow-control techniques such as token-bucket rate limiting and circuit breakers.

Key considerations include clock drift, latency amplification, fairness between clients, idempotence of operations, and proper handling of failure modes when the delay cannot be enforced. Incorrect or overly aggressive delays can increase tail latency or cause starvation.

See also: backpressure, rate limiting, delayed queue, load shedding, circuit breaker.