It looks like I can reproducibly get dagster stuck in the ActiveExecution multiprocess loop. It looks as if,

get_steps_to_execute

returns 0 steps, although I should have processes that are becoming open (nothing is actually executing - they are stuck in preparing). While I don't know dagster internals well, it looks like dagster's multiprocessing classes are not actually closing the processes. For example, I have active_iters with processes that do not appear as active in the UI. Would love to get someone's eyes on this, as it's either user error or a bad bug.

Hi Simon - is there any chance you could share code that's hitting this? It's true that Dagster doesn't close down the subprocesses, but they would typically close themselves down once they're finishing the steps. My suspicion here would be that there's something in your code that's hanging at some point while executing the steps

@daniel Thank you for getting back to me. lmk check what I can share - definitely want to enable to you to debug this.

No problem - you can also send over the Debug file for a run that's hitting this: - the answer for why its hanging is pretty likely to be within the code, but the debug file might help narrow down exactly where its likely to be sutck