@Marvin, How do I resume interrupted runs from the last successful point without restarting the flow from the beginning?

To resume interrupted flow runs in Prefect 3.x without restarting from the beginning, you can use the

resume_flow_run

function. This function is part of Prefect's top-level API and allows you to resume a flow run from a paused state. Here's a concise guide: 1. Pause and Resume: When a flow run is interrupted, it can be paused using

pause_flow_run

. Later, you can resume it using

resume_flow_run

. 2. Implementation: Ensure your flow is designed to handle resumption by checking the state of tasks and skipping those that have already completed successfully. 3. Documentation: For more detailed implementation instructions, refer to the Prefect documentation on flow runs. Here's a brief look at the relevant functions from the Prefect API: -

pause_flow_run

-

resume_flow_run

These functions are designed to handle flow run states efficiently, allowing for resumption from the last successful task rather than starting over. If you need further assistance with the implementation, feel free to ask!

@Marvin How can I resume a failed run from the last successful point?

Resuming a failed flow run in Prefect 3.x from the last successful point requires understanding how to handle task states and retries. Here's a concise guide: 1. Task State Management: Prefect tracks the state of each task. If a task fails, it can transition to a

Failed

state. Prefect provides utilities to handle these states and potentially retry tasks. 2. Retry Logic: Implement retry logic within your flow or task definitions. This allows tasks to automatically retry upon failure, potentially up to a specified number of times. Utilize the

retries

parameter when defining tasks. 3. Manual Resumption: If manual intervention is required, you can inspect the flow run's state and manually trigger retries or re-execution of specific tasks that failed. 4. Documentation: For more details, you can explore the Prefect debugging tutorial and the source code for task engine which handles task states and retries. By properly managing task states and using retries, you can effectively resume flow runs from the last successful task rather than starting over. If you need more specific implementation guidance, feel free to ask!

@Marvin How to restart all the failed flows from beginning. I have 20 failed runs of different flows due to infrastructure problem.

To restart all failed flow runs from the beginning in Prefect 3.x, you need to handle each flow run individually, as Prefect does not provide a direct bulk restart feature. Here's a general approach: 1. Identify Failed Runs: Use the Prefect UI or API to list all flow runs and filter those with a

Failed

state. 2. Restart Each Flow: For each failed flow run, initiate a new run of the corresponding flow. This can be done programmatically using the Prefect client. 3. Use Prefect Client: - Connect to your Prefect server using

get_client()

. - Retrieve the list of failed flow runs. - For each failed flow run, submit a new run using the flow's deployment or configuration. Here's a basic example using the Prefect client:

python
from prefect import get_client

async def restart_failed_flows():
    client = await get_client()
    async with client:
        # Retrieve all flow runs
        flow_runs = await client.read_flow_runs()
        
        # Filter for failed runs
        failed_runs = [run for run in flow_runs if run.state.is_failed()]
        
        for run in failed_runs:
            # Restart the flow by creating a new flow run
            await client.create_flow_run_from_deployment(deployment_id=run.deployment_id)

# Run the restart function
await restart_failed_flows()

This script connects to the Prefect server, retrieves all flow runs, filters out the failed ones, and restarts them by creating new flow runs from their deployments. Adjust the logic as needed to fit your specific infrastructure and deployment setup. For more detailed guidance, refer to the Prefect documentation. If you have more specific questions, feel free to ask!