@Marvin Can I limit the number of tasks run concurrently for a given flow?

Yes, you can limit the number of tasks that run concurrently in a given flow using Prefect’s concurrency management features. You can achieve this by setting concurrency limits either at the task level or the flow level. ### Approaches: 1. Using Task Tags: - Task concurrency limits are set using tags. - You can configure these limits via the Prefect CLI, the Prefect API, or through the Prefect server UI or Prefect Cloud.

python
   from prefect import flow, task
   from prefect.concurrency.sync import concurrency

   @task(tags=["limited-task"])
   def my_task(x, y):
       with concurrency("limited-task", occupy=1):
           return x + y
    
   @flow
   def my_flow():
       for x, y in [(1, 2), (2, 3), (3, 4), (4, 5)]:
           my_task.submit(x, y)

   if __name__ == "__main__":
       my_flow()

This example uses the

concurrency

context manager and sets a concurrency limit on a specific tag. 2. Using Global Concurrency Limits: - Prefect lets you set global concurrency limits that span multiple tasks and flow runs. - These limits are configured through work pools and queues and can be adjusted using the Prefect CLI or API.

shell
   prefect concurrency-limit create "my_limit" --limit 10

This command sets a global concurrency limit of 10 for tasks tagged with

my_limit

. 3. Configuring the Prefect Client: - You can also set and inspect limits programmatically using the Prefect Client.

python
   from prefect import get_client

   async def set_concurrency_limit():
       async with get_client() as client:
           await client.create_concurrency_limit("my_limit", limit=10)

   asyncio.run(set_concurrency_limit())

### Documentation and Resources: - Concurrency Management: Prefect Concurrency Management - Concurrency Limits Guide: Global Concurrency Limits For a more detailed explanation, you might want to check these resources or explore the Prefect GitHub issues for any related discussions on the topic. ### Relevant GitHub Issues: - Concurrency Limit Setting "Active Slots" - Check concurrency limit before submitting tasks - Global concurrency not applied to tasks with DaskTaskRunner These links might offer additional insight or potential solutions if you encounter specific issues related to concurrency limits.