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<@ULVA73B9P> I have a flow with multiple subflows....
# ask-marvin
t
@Marvin I have a flow with multiple subflows. How do I configure the parent flow to continue on with the other sub-flows in case one of the sub-flow errors out?
m
To configure a parent flow to continue executing other subflows even if one subflow fails, you can use the 
allow_failure
feature in Prefect 3.x. This feature allows a flow or task to continue despite failures in its dependencies. Here's a concise guide on how you can implement this: 1. Use `allow_failure`: When defining your subflows, you can set 
allow_failure
to 
True
. This setting allows the parent flow to proceed with subsequent subflows even if one of them fails. 2. Example Implementation:
Copy code
python
   from prefect import flow, task

   @task
   def task_a():
       # Some task logic
       pass

   @task
   def task_b():
       # Task that might fail
       raise Exception("Failure in task_b")

   @task
   def task_c():
       # Some task logic
       pass

   @flow
   def parent_flow():
       task_a()
       try:
           task_b()
       except Exception as e:
           print(f"Continuing despite error in task_b: {e}")
       task_c()

   if __name__ == "__main__":
       parent_flow()
3. Documentation and Resources: - Prefect 3.x Documentation on Error Handling - Prefect GitHub Source Code This setup ensures that your parent flow will not be halted by an error in one of the subflows, allowing the remaining subflows to execute as planned.
To configure a parent flow to continue with other subflows even if one of them errors out, you can use the 
allow_failure
feature in Prefect 3.x. This allows you to handle errors gracefully and ensure that the remaining subflows continue execution. Here's a concise way to implement this: 1. Use `allow_failure`: This utility can be used to wrap subflows or tasks that might fail, allowing the parent flow to proceed without interruption. 2. Example Implementation:
Copy code
python
   from prefect import flow, task, allow_failure

   @task
   def my_subflow_task():
       # Your subflow logic here
       pass

   @flow
   def parent_flow():
       results = []
       # Wrap subflows in allow_failure
       for subflow in [my_subflow_task, my_subflow_task, my_subflow_task]:
           result = allow_failure(subflow)()
           results.append(result)
       return results

   if __name__ == "__main__":
       parent_flow()
In this example, 
allow_failure(subflow)()
ensures that if a subflow task fails, it won't prevent the other subflows from running. 3. Documentation References: - For more detailed information, you can explore the Prefect documentation. By using 
allow_failure
, you ensure that your parent flow continues executing other subflows even if one encounters an error. If you need further customization or error handling, Prefect's logging and state management features can help.
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