Hi All - hopefully an easy question: What is the p...
# ask-communitys
Seth Goodman
10/21/2022, 3:50 PMHi All - hopefully an easy question: What is the proper way to redefine an existing task? E.g., In interactive mode I create my_task, then edit my_task, and I get an error of "OSError: could not get source code". Using 2.6.4
✅ 1
j
Jean Luciano
10/21/2022, 4:12 PMDid you build the deployment after making changes to your task?
s
Seth Goodman
10/21/2022, 4:17 PMI rebuilt the flow the task was running in before calling the flow (editing/redefining the flow instead of the task presents the same error), but I haven't created an actual deployment of the flow - I have just been testing the functionality in an interactive python session
Seth Goodman
10/21/2022, 4:20 PM@Jean Luciano barebones example to replicate:
Copy code
from prefect import task, flow
@task
def my_task():
print("hello")
@flow
def my_flow():
my_task.submit()
my_flow()Seth Goodman
10/21/2022, 4:21 PMthe error is when i then try to do:
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@task
def my_task():
print("goodbye")
# error here after trying to redefine task
@flow
def my_flow():
my_task.submit()
my_flow()j
Jean Luciano
10/21/2022, 4:48 PMDo you get the same error by calling the task directly i.e
my_task()s
Seth Goodman
10/21/2022, 4:50 PMthe error is when just defining the task, not actually trying to call it
Seth Goodman
10/21/2022, 4:51 PMso even if i just put the exact same task function into my terminal twice i would get the error on the second one
Seth Goodman
10/21/2022, 4:51 PM Copy code
@task
def my_task():
print("hello")
@task
def my_task():
print("hello")
# error trigger by second instancej
Jean Luciano
10/21/2022, 5:10 PMIs this using ipython?
s
Seth Goodman
10/21/2022, 5:13 PMjust standard shell interpreter
r
Ryan Peden
10/21/2022, 9:08 PMThis happens in interactive mode because when you create a new flow or task with the same name as an existing flow or task, Prefect tries to load the file where the redefinition happened so it can give you a friendly warning message. But, of course, that doesn't work if your code isn't in a file 🙂
Normally, you wouldn't need to redefine an existing task because there's usually a better way to accomplish your goals. But if you just want to do a few quick experiments in an interactive session, I can see why redefining and re-running tasks would be handy.
A quick way to work around this would be giving the tasks different names so Prefect doesn't see the redefinition as a duplicate. In that case, your sample would look like:
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@task(name="1")
def my_task():
print("hello")
@task(name="2")
def my_task():
print("hello")
# Prefect remains happy Copy code
import uuid
from prefect import task as _task
task = lambda fn, **kwargs: _task(fn, name=str(uuid.uuid4()), **kwargs)
# then, these should work
@task
def my_task():
print("hello")
@task
def my_task():
print("hello")
# Prefect still happy👍 1