Hi all In Prefect 2 is the default task runner the `Concurre

Question

Hi all In Prefect 2 is the default task runner the `Concurrent` or `Sequential` In one section the docs say the default is `Concurrent` but then in another section they say Make sure you use ` submit ` to run your task with a task runner Calling the task directly without ` submit ` from within a flow will run the task sequentially instead of using a specified task runner which seems to imply that the default is actually `Sequential`

Khuyen Tran · Answer

It is Concurrent However you cannot use a task runner without using ` submit`

Khuyen Tran · Answer

so you right without ` submit` the tasks will run sequentially

kiran · Answer

I m able to run this code and it works should it not ``` task def say hello name print f hello name task def say goodbye name print f goodbye name flow task runner=SequentialTaskRunner def greetings names for name in names say hello submit name say goodbye submit name say hello name say goodbye name greetings arthur trillian ford marvin ```

Khuyen Tran · Answer

yes it works But it will not run concurrently

Khuyen Tran · Answer

since your task runner is SequentialTaskRunner

kiran · Answer

Yes that was the intention So then using submit with Sequential is not necessary it seems

kiran · Answer

Also so the default is Concurrent but if you don t submit your tasks they ll run sequentially even though the default is Concurrent ie is would this one run Concurrently or Sequentially ``` task def say hello name print f hello name task def say goodbye name print f goodbye name flow def greetings names for name in names say hello name say goodbye name greetings arthur trillian ford marvin ```

Khuyen Tran · Answer

< terrence> kiran said that that part of the docs specifically for Sequential is a bit confusing because it seemed redundant with the submit but wasn t totally clear Perhaps we should remove the

terrence · Answer

Thanks for raising this question I ll look at reworking these docs to make it more clear It does get a little confusing and we probably shouldn t bring in the task runner at all initially Bottom line 1 You must ` submit ` to use a task runner 2 Even if you import and specify a task runner on the flow if you don t `submit` it s not submitted to the task runner