@Marvin I am calling a task from an

on_failure

hook (which works fine). Is this going to set me up for some weird side effects down the road?

To provide a precise answer regarding potential side effects in Prefect when calling a task from the

on_failure

hook, I need to know the version of Prefect you are using. The behavior and implementation details can vary between Prefect 2.x and Prefect 3.x. Please confirm the version of Prefect you’re using. If you're unsure about the version, you can check it with the following Python command:

python
import prefect
print(prefect.__version__)

Once you provide the version, I'll look up the appropriate documentation and provide information regarding potential side effects.

@Marvin I'm using prefect 2.19 but will upgrade to v3 in a few months.

In Prefect, using the

on_failure

hook to call a task is a supported pattern and generally does not lead to any unexpected side effects. Here are the key points regarding

on_failure

hooks and tasks: ### Prefect 2.x 1. State Change Hooks Overview: Prefect allows defining hooks to execute code when flow or task states change. An example use case is sending notifications when a task fails. This is done by specifying a function in the

on_failure

parameter. 2. Retries Consideration: When you set up retries along with

on_failure

, the hook will not execute until all retries are exhausted. This prevents premature execution of failure handlers. Source: - State Change Hooks - Prefect 2.x Documentation - State Concept - Prefect 2.x Documentation ### Prefect 3.x 1. Transition Customization: In Prefect 3.x, the

on_failure

hook works similarly, allowing you to run custom code in response to task or flow failures. This might include logging, retry logic, cleanup actions, etc. 2. Example Usage: You can attach hooks in the

@flow

or

@task

decorators, specifying the functions to run on state changes (

on_failure

,

on_completion

, etc.). Source: - Manage States - Prefect 3.x Documentation ### General Advice - State Management: When defining

on_failure

hooks, ensure that the logic within these hooks properly handles the state and any necessary resource cleanup or notifications to avoid redundant actions. - Synchronous vs Asynchronous Tasks: Depending on the complexity of tasks triggered in the hook, consider implications on performance and resource usage. By carefully structuring your hooks, you can avoid side effects and ensure robust error handling in your workflows. If you have any specific scenarios or further questions, feel free to ask!

thank you @Marvin!

You're welcome! If you have any more questions or need further assistance as you continue with Prefect or any other topic, feel free to reach out. Happy coding, and good luck with your project!