Have a general question about migrating from Prefect 1 0 to Prefect Community #ask-community

Have a general question about migrating from Prefe...

Keith

08/06/2022, 12:59 AM

Have a general question about migrating from Prefect 1.0 to 2.0. In 1.0 there was a generic

upstream_tasks

parameter that you could pass to tasks so that each task knew to wait for the previous one to run. Through my reading of the documentation it seems like this is not necessary anymore b/c everything should run like it would in Python so it basically defaults to a sequential executor. Is this the correct logic? Obviously this story changes a bit when adding in the different

Task Runners

but just wanted to confirm that using default code blocks that tasks run in sequence and won't run the next task until the previous one is complete.

✅ 3

Nico Neumann

08/06/2022, 1:04 AM

In prefect 2.0 it was unified to

wait_for

As for as I know default should be to run task in sequential order, so there is no need to include

wait_for

🙏 1

🙌 2

Nico Neumann

08/06/2022, 1:07 AM

Just tried it:

Copy code

from prefect import flow, get_run_logger, task


@task
def task1():
    logger = get_run_logger()
    while True:
        <http://logger.info|logger.info>("task1")


@task
def task2():
    logger = get_run_logger()
    while True:
        <http://logger.info|logger.info>("task2")


@flow(name="Test Flow")
def flow_run():
    task1()
    raise Exception()
    task2()


flow_run()

Nico Neumann

08/06/2022, 1:07 AM

It prints task1 forever and never raises the Exception because it waits forever for the first task to finish

Nico Neumann

08/06/2022, 1:37 AM

@Keith Just had a look in the documentation: The default task_runner is