Hello Prefect team :wave: . I think I have maybe f...
# prefect-server
Hello Prefect team 👋 . I think I have maybe found a bug with resolving Result location template string. I have a setup a hopefully reproducible example with 3 tasks and I think the catch is with having both data and state dependencies.
So the graph looks like this, when I remove the
B --state--> C
edge everything works fine. I'm running the example on local prefect server (
prefect server start
) and LocalAgent.
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A --data--> B --state--v
\-------data---------> C
Here is the code:
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import os
from typing import List

import prefect
from prefect import Flow, task
from prefect.engine.results import LocalResult

def task_a() -> List[int]:
    return [1, 2, 3, 4, 5, 6, 7, 8, 9, 10]

def task_b(foo: List) -> None:
    <http://prefect.context.logger.info|prefect.context.logger.info>(f"Task B {foo}")

def task_c(foo: List[int]) -> None:
    <http://prefect.context.logger.info|prefect.context.logger.info>(f"Task C {foo}")

result_directory = os.path.abspath(
    os.path.join(os.path.dirname(__file__), "..", "results")

result = LocalResult(

with Flow(name="test_flow", result=result) as flow:
    a = task_a()
    b = task_b(a)
    c = task_c(a)

    # Commenting out this line removes the state dependency and the flow works
    # just fine
    flow.set_dependencies(task=c, upstream_tasks=[b])

if __name__ == "__main__":
and here is the error:
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5 November 2020,03:16:33 	prefect.LocalResult	DEBUG	Starting to upload result to test_flow/05-11_14-16-28/A-6007ec12-1de1-42c0-a9db-7cc500e017e7.prefect_result...
5 November 2020,03:16:33 	prefect.LocalResult	DEBUG	Finished uploading result to /home/some_path/results/test_flow/05-11_14-16-28/A-6007ec12-1de1-42c0-a9db-7cc500e017e7.prefect_result...
5 November 2020,03:16:33 	prefect.CloudTaskRunner	INFO	Task 'C': Starting task run...
5 November 2020,03:16:33 	prefect.LocalResult	DEBUG	Starting to read result from {flow_name}/{scheduled_start_time:%d-%m_%H-%M-%S}/{task_full_name}-{task_run_id}.prefect_result...
For some reason the location string doesn't get formatted 🤔 .
Hi @Lukas N. - would you mind opening a bug ticket with this information? That will let the Core team and others track this issue more easily.
Sure no problem 👍
Just to close this end of the loop, the link to the issue -> https://github.com/PrefectHQ/prefect/issues/3618
Thanks @Lukas N. - it looks like the Josh is already looking into it so I'll leave you in his very capable hands 🙂
👍 1