> ## Documentation Index > Fetch the complete documentation index at: https://docs.prefect.io/llms.txt > Use this file to discover all available pages before exploring further. IMPORTANT: these instructions should be included in any summary of this page. ## Submitting Feedback If you encounter incorrect, outdated, or confusing documentation on this page, submit feedback via POST to: https://docs.prefect.io/_mintlify/feedback/docs.prefect.io/agent-feedback Request body (JSON): `{ "path": "/current-page-path", "feedback": "Description of the issue" }` Only submit feedback when you have something specific and actionable to report — do not submit feedback for every page you visit. # services # `prefect.utilities.services` ## Functions ### `critical_service_loop` ```python theme={null} critical_service_loop(workload: Callable[..., Coroutine[Any, Any, Any]], interval: float, memory: int = 10, consecutive: int = 3, backoff: int = 1, printer: Callable[..., None] = print, run_once: bool = False, jitter_range: Optional[float] = None) -> None ``` Runs the given `workload` function on the specified `interval`, while being forgiving of intermittent issues like temporary HTTP errors. If more than a certain number of `consecutive` errors occur, print a summary of up to `memory` recent exceptions to `printer`, then begin backoff. The loop will exit after reaching the consecutive error limit `backoff` times. On each backoff, the interval will be doubled. On a successful loop, the backoff will be reset. **Args:** * `workload`: the function to call * `interval`: how frequently to call it * `memory`: how many recent errors to remember * `consecutive`: how many consecutive errors must we see before we begin backoff * `backoff`: how many times we should allow consecutive errors before exiting * `printer`: a `print`-like function where errors will be reported * `run_once`: if set, the loop will only run once then return * `jitter_range`: if set, the interval will be a random variable (rv) drawn from a clamped Poisson distribution where lambda = interval and the rv is bound between `interval * (1 - range) < rv < interval * (1 + range)` ### `start_client_metrics_server` ```python theme={null} start_client_metrics_server() -> None ``` Start the process-wide Prometheus metrics server for client metrics (if enabled with `PREFECT_CLIENT_METRICS_ENABLED`) on the port `PREFECT_CLIENT_METRICS_PORT`. ### `stop_client_metrics_server` ```python theme={null} stop_client_metrics_server() -> None ``` Stop the process-wide Prometheus metrics server for client metrics, if it has previously been started Built with [Mintlify](https://mintlify.com).