Observer-task running continuesly - best practice?

[thp44]

Hi,
I have a observer-task I want to always run with my other time based tasks. What would be the best practice for a continuously running "task"/observer in rocketry?
Can't seem to find it in the documentation.

[Miksus]

Hi!

Hmm, it indeed seems I have forgotten to mention about the permanent_task:

@app.task(permanent_task=True, on_startup=True, execution="async")
async def do_constantly():
    while True:
        ...
        await asyncio.sleep(0)

There are a couple of reasons to use this. Without it, the task risks being timeout. If you put infinite as the timeout, there is a problem in the shutdown: the scheduler waits for the task to finish by default (which will never happen). This attribute signals to the scheduler that the task should never timeout but it should not wait it to finish when the scheduler shuts down.

You can use any execution with the task except main as then the task blocks everything. Also, note that I used the on_startup=True, this by default makes the task be started in the startup cycle (no need to put a start condition).

I possibly rename the permanent_task to permanent in the future (as the word task is pointless there) but I'll introduce a warning when that happens.

Did I answer to the question?

[thp44]

Yup! Thank you very much for quick and detailed answer. Can't wish for more. 💯 👍

[Miksus]

No problem! Thanks for the question by the way. I'll make an issue to improve the documentation about the permanent tasks (as there is indeed no mention of those).