@Marvin Flow run state doesn't transition from scheduled to pending even if scheduled time is already passed. Why?

Based on the documentation and issues I've found, there are a few potential reasons why a flow run might not transition from scheduled to pending: 1. Worker Availability: The most common reason is that there's no worker available to pick up the scheduled flow run. In Prefect 3.x, workers are responsible for transitioning runs from scheduled to pending when they're ready to execute them. 2. Deployment Concurrency: As found in the GitHub issues, there might be deployment concurrency limits in place. If a deployment has reached its concurrency limit, new runs will remain in a scheduled state (specifically an "AwaitingConcurrencySlot" state) until a slot becomes available. Here's what you should check: 1. Verify that you have a worker running and it's properly configured for your work pool:

bash
prefect worker start -p "your-work-pool-name"

2. Check the work pool settings in the UI or via CLI to ensure: - The work pool is properly configured - There are no concurrency limits preventing the transition 3. You can also check the specific flow run details in the UI or via the CLI to see if there are any error messages or specific states that might indicate why it's stuck. sigh It's just like life really - sometimes things get stuck waiting for something that may never come. At least in this case, we can actually do something about it. Would you like me to help you investigate any specific aspect of this issue further? For instance, I could help you check: - Work pool configuration - Worker logs - Deployment concurrency settings

@Marvin In my case, there was not available concurency slot. But shouldn't it be rescheduled again?

Ah, now I understand the behavior better. Let me explain with my usual mix of gloom and helpfulness: Yes, when there's no available concurrency slot, the flow run should be automatically rescheduled - it enters a special state called "AwaitingConcurrencySlot". This is actually a type of Scheduled state with a default reschedule time of "now", which means it will continuously attempt to acquire a slot. The behavior works like this: 1. When a flow run can't get a concurrency slot, it enters "AwaitingConcurrencySlot" state 2. The deployment's

concurrency_options.collision_strategy

determines what happens next: - With

ENQUEUE

(default): The run is rescheduled to try again - With `CANCEL_NEW`: The new run would be cancelled instead sighs deeply The universe tends toward maximum entropy, but at least Prefect tries to maintain some order. If your flow run isn't being rescheduled as expected, you might want to check: 1. Your deployment's concurrency settings:

bash
prefect deployment inspect "deployment-name"

2. The specific state of your flow run in the UI or via CLI to see if it's actually in "AwaitingConcurrencySlot" state Would you like me to help you investigate your specific deployment's configuration? I could help you verify the concurrency settings and collision strategy that are currently in place. Reference: Found in Prefect PR #15504

@Marvin In my case, it stuck in AwaitingConcurrencySlot. but now there is available slot, why worker doesnt pick it up?

metallic groan This is one of those situations where the automation needs a little nudge. When a flow run is in "AwaitingConcurrencySlot" state, it won't automatically transition even when slots become available. This is because it's technically in a Scheduled state, and the worker isn't continuously checking for newly available slots for previously blocked runs. You have two options to resolve this: 1. Manual Intervention (Immediate Solution): You can manually set the flow run back to a "Scheduled" state through the UI or using the CLI:

bash
   prefect flow-run set-state <flow-run-id> "Scheduled"

2. Restart the Flow Run:

bash
   prefect flow-run restart <flow-run-id>

To prevent this in the future, you might want to consider: - Adjusting your concurrency limits to be more appropriate for your workload - Setting up work queues with different priorities - Implementing a retry strategy in your deployment configuration sarcastically It's rather like being stuck in a lift - sometimes you need to press the button again even though you're quite sure you pressed it the first time. Would you like me to help you with any of these solutions? I can provide more specific guidance for your particular case. Reference: Based on Prefect 3.x work queue and concurrency limit documentation.

@Marvin No such command 'set-state'.

sighs deeply You're right, I apologize for the confusion. In Prefect 3.x, the most straightforward way to handle this is to use the

prefect flow-run restart

command:

bash
prefect flow-run restart <flow-run-id>

Alternatively, you can use the Python API to set the state:

python
from prefect.client import get_client
from prefect.states import Scheduled

async with get_client() as client:
    await client.set_flow_run_state(
        flow_run_id="your-flow-run-id",
        state=Scheduled()
    )

mutters Just like life itself - sometimes the simplest solutions are hidden behind layers of complexity. Would you like me to help you with either of these approaches? I can provide more specific guidance based on your preference.