@Marvin How can I check the state of a task during its execution, specifically to learn which retry it is on?

To provide a precise answer, I need to know which version of Prefect you are using. Could you please let me know? If you're unsure, I can help guide you on how to find that information.

@Marvin Prefect 2.20.6

In Prefect 2.20.6, it's not straightforward to determine the current retry attempt of a task during its execution, as Prefect doesn't directly expose a retry count within the task context. However, you can implement a custom retry handler to manage retry logic based on certain conditions. Here's an example using a custom

retry_condition_fn

, which allows you to define logic that determines whether a task should retry:

python
import httpx
from prefect import flow, task

def retry_handler(task, task_run, state) -> bool:
    """This is a custom retry handler to handle when we want to retry a task"""
    try:
        # Attempt to get the result of the task
        state.result()
    except httpx.HTTPStatusError as exc:
        # Retry on any HTTP status code that is not 401 or 404
        do_not_retry_on_these_codes = [401, 404]
        return exc.response.status_code not in do_not_retry_on_these_codes
    except httpx.ConnectError:
        # Do not retry
        return False
    except:
        # For any other exception, retry
        return True

@task(retries=3, retry_condition_fn=retry_handler)
def my_task():
    return 1 / 0  # This will cause an exception and trigger retries

@flow
def my_flow():
    my_task()

if __name__ == "__main__":
    my_flow()

In this example, the

retry_handler

can be customized further to maintain a retry count using external storage or logging mechanisms, as Prefect doesn't inherently provide a direct retry count during execution. For additional context, you might want to check out issues and discussions related to retry functionality in Prefect GitHub repo issue 6787. It discusses the need for better retry notifications and handling. Feel free to ask if you need further assistance!