Retrier

Retrier refers to a software component or design pattern that automatically reissues a failed operation according to a defined policy. The aim is to recover from transient faults such as brief network outages or temporary unavailability of a service, without requiring user intervention. A retrier may be implemented inside a client library, a service, or as a standalone utility.

A retrier operates under a retry policy that specifies how many attempts may be made, how long to wait between attempts, and which delay strategy to use. Common approaches include fixed delays, linear backoff, and exponential backoff, often combined with jitter to reduce synchronized retries. Some policies also bound total elapsed time or cap the number of attempts. Implementations usually categorize errors into retryable (transient) and non-retryable (permanent).

Safe retrier use typically requires idempotent operations or side-effect-free retries to avoid duplicate effects or inconsistent state. Retries can be performed synchronously within a calling thread or asynchronously by scheduling subsequent attempts. In distributed systems, retriers are commonly used together with circuit breakers and backpressure mechanisms to prevent cascading failures.

Common applications include retrying HTTP requests, database queries, message processing, and worker tasks in queues. When used carelessly, retriers can increase latency, cause duplicate processing, or mask underlying instability; good practice emphasizes monitoring, proper error classification, and testing with realistic backoff configurations.