Retrying

Retrying is a technique used to handle transient failures by repeating an operation after it fails. It is widely used in computer systems and communications to improve reliability in the presence of short-lived errors.

In software and networks, a retry loop repeatedly performs an operation such as a network request, database access, or message publish. If the operation fails due to a recoverable condition, the system waits for a delay and tries again.

Common strategies include fixed-delay retries, progressive backoff with exponential growth of the delay, and sometimes jitter to reduce the chance that multiple clients retry in sync. Retries are usually bounded by a maximum number of attempts or a total timeout.

Safety considerations include ensuring operations are idempotent or that retries do not cause duplicate effects. Timeouts, circuit breakers, and appropriate error classification help prevent cascading failures and wasted resources.

Implementation and patterns vary; libraries commonly expose retry policies with configurable backoff, max retries, and jitter. More retries increase reliability but add latency and load, while excessive retries can worsen congestion.

Testing and monitoring are important, including logging retry counts, success rates after retries, and alerting on unusual retry patterns. Synthetic tests can help validate backoff behavior and failure modes.