Have a general question about migrating from Prefect 1 0 to

Question

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

Nico Neumann · Answer

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`

Nico Neumann · Answer

Just tried it ```from prefect import flow get run logger task task def task1 logger = get run logger while True task1 task def task2 logger = get run logger while True task2 flow name= Test Flow def flow run task1 raise Exception task2 flow run ```

Nico Neumann · Answer

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

Nico Neumann · Answer

< Keith> Just had a look in the documentation The default task runner is `ConcurrentTaskRunner` Depends on your use case you might want to switch to `SequentialTaskRunner`

Nico Neumann · Answer

< Anna Geller> s message explains it well that it only runs in parallel when explicitly calling with submit or map