I have a flow that runs 121 mapped tasks two of those tasks

Question

I have a flow that runs 121 mapped tasks two of those tasks failed however the overall flow was nor marked as failed

Constantino Schillebeeckx · Answer

Both tasks failed because gt No heartbeat detected from the remote task marking the run as failed

Kevin Kho · Answer

So for the heartbeat it might be more stable with <https docs prefect io orchestration faq faq html why does prefect mark flow runs with no heartbeat detected from the remote task marking the run as failed|threads> Have you done that With the flow marked as failed are these mapped tasks the last tasks in your flow The final state is determined by the `terminal tasks` so you can explicit make them terminal tasks by doing ```flow terminal tasks = ```

Constantino Schillebeeckx · Answer

no these tasks run in the middle of the flow

Constantino Schillebeeckx · Answer

in general though even if the task fails shouldn t the flow be marked as failed

Kevin Kho · Answer

not really unless you explicitly specify for example if you have a flow with A gt B gt C and B fails but you force C to run and it s successful I think this is considered a success by default because C is the terminal task in the graph

Kevin Kho · Answer

normally failure would propagate and fail the last task as well but in the event it doesn t you have to be explicit about what task makes the flow fail

Constantino Schillebeeckx · Answer

i see i noticed in this particular case the failed tasks didn t report failure until the all other tasks had run in the flow which confuses me so technically the terminal task was a success

Constantino Schillebeeckx · Answer

to be a bit more explicit i have mapped tasks `L1` `Ln` and then I have a task `do dbt` which is a downstream dependencies of all the mapped tasks `L` one of those mapped tasks stopped reporting a heartbeat back and eventually `do dbt` just started running and passed then `Ln` was finally set as failed

Kevin Kho · Answer

it sounds like the dependency was not set right how did you make `t` a downstream

Kevin Kho · Answer

That looks perfectly right though I would try setting ```flow terminal tasks = L ``` but I m not 100 sure on the mapped task behavior

Constantino Schillebeeckx · Answer

but `L` aren t terminal tasks and `do dbt` should only run after all of `L` is finished

Constantino Schillebeeckx · Answer

is it bad form to set all tasks as terminal tasks to ensure this behavior doesn t happen

Kevin Kho · Answer

My bad not terminal task

Kevin Kho · Answer

`flow reference tasks= `

Constantino Schillebeeckx · Answer

i see that does seem like a valid workaround i m curious though why `do dbt` would run if one of the mapped `L` tasks has a missing heartbeat

Kevin Kho · Answer

Yeah I am not sure about that at the moment either

Constantino Schillebeeckx · Answer

I ve just bumped up my container resources and it looks like i m not getting heartbeat issues anymore thank you docs i m wondering if there s a bug for up down stream task dependencies when this heartbeat issue comes up

Kevin Kho · Answer

Potentially I can see that