Hi I have a question about using two schedules in the flow o Prefect Community #ask-community

Hi! I have a question about using two schedules in...

Alexander Belikov

04/12/2022, 8:59 AM

Hi! I have a question about using two schedules in the flow of flows construct: I posted it here https://stackoverflow.com/questions/71839812/prefect-loop-over-flows-two-schedules

Anna Geller

04/12/2022, 10:54 AM

I saw Franznist gave a great answer. Are you good now? The main issue in your Flow is that you are calling a Flow from within a task - this is not supported, especially not using

flow.run()

since this is meant only for local development.

Anna Geller

04/12/2022, 11:14 AM

Some additional notes: • scheduling a flow every second is not possible 🙂 the lowest we can do is every 1 minute in Prefect 1.0 • when you print in your tasks, you need to add log_stdout arg:

@task(log_stdout=True)

• to add parameters for the "sleep time" in between runs, you can also use a Parameter task • instead of calling a flow, you could also call a normal parametrized Python function when looping - perhaps that would be easier to manage?

Anna Geller

04/12/2022, 11:18 AM

btw your use case seems better suited for Prefect 2.0 - perhaps it's easier to do it directly with 2.0 if you're just getting started?

Alexander Belikov

04/12/2022, 12:36 PM

Thanks a lot! Franznist's answer is great indeed. I was wondering if there is a "prefectonic" way of doing

sleep

Calling a task from a flow is not supported, but it works (and the reference I gave cite prefect slack as the source of recommendation), so will you called a hack that should be avoided?

instead of calling a flow, you could also call a normal parametrized Python function when looping

Indeed it would easier

Alexander Belikov

04/12/2022, 12:37 PM

thanks!

Anna Geller

04/12/2022, 12:44 PM

Calling a task from a flow is not supported, but it works

Calling a task from a Flow is supported, but calling a Flow from a task is not - perhaps you misread my message? 🙂 Regarding Gaetan's StackOverflow answer, this is not a pattern I would recommend.

I was wondering if there is a "prefectonic" way of doing
sleep

You can alternatively use the

create_flow_run

task with a custom

scheduled_start_time

but this will have the same effect.

Alexander Belikov

04/12/2022, 12:49 PM

oh, yes - it's typo, I was referring to your words and I meant to say calling a flow from a task. Gotcha. thank you, using

scheduled_start_time

sounds great, will check it out

Anna Geller

04/12/2022, 1:02 PM

to be transparent, I don't think that using

scheduled_start_time

is the right solution to your problem, it was only to answer your question

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