@Marvin is there a way to limit the number of threads or processes spun up by concurrent/dask task runner in the deployment.yaml?

To limit the number of threads or processes used by the

ConcurrentTaskRunner

or

DaskTaskRunner

in a deployment, you can configure concurrency limits using task tags or set parameters in the task runner configuration. Here’s an outline based on the documentation: 1. Task Concurrency Limits: You can limit the number of concurrently running tasks by using task tags and setting concurrency limits. This approach ensures that tasks with the specified tag do not exceed the defined limit.

yaml
    # Example deployment.yaml snippet
    flow:
        - name: my_flow
          task_runner:
              type: ConcurrentTaskRunner
              max_workers: 10  # Set the maximum number of workers
          tags: ["my_task_tag"]
          concurrency_limits:
              - tag: "my_task_tag"
                concurrency: 10  # Limit tasks with this tag to 10 concurrent runs.

2. DaskTaskRunner Configuration: You can set the number of workers for a

DaskTaskRunner

directly in the configuration. Dask allows specifying a fixed number of workers or using adaptive scaling to adjust the number of workers based on the workload.

yaml
    # Example deployment.yaml for DaskTaskRunner
    flow:
        - name: my_flow
          task_runner:
              type: DaskTaskRunner
              cluster_class: dask.distributed.LocalCluster
              cluster_kwargs:
                  n_workers: 10  # Set the maximum number of workers

3. Adaptive Scaling: For

DaskTaskRunner

, adaptive scaling can be used to define a range for the number of workers.

yaml
    # Example deployment.yaml for adaptive scaling with DaskTaskRunner
    flow:
        - name: my_flow
          task_runner:
              type: DaskTaskRunner
              cluster_class: dask.distributed.LocalCluster
              cluster_kwargs:
                  n_workers: 1  # Starting workers
                  processes: True
              adapt_kwargs:
                  minimum: 1
                  maximum: 10  # Max workers

4. Documentation References: - Prefect Task Runners - Prefect Task Concurrency Limits - Prefect Deployment Guide You can adjust the specifics according to your deployment setup and requirements.

@Marvin can I specify the task runner in the deployment yaml?

Yes, you can specify the task runner directly in the

deployment.yaml

for a Prefect deployment. Here is an example of how to do this: ### Example

deployment.yaml

yaml
# Example deployment.yaml snippet
version: 1

flows:
  - name: my_flow
    parameters: {}
    task_runner:
      type: ConcurrentTaskRunner  # Specify your task runner here
      max_workers: 10             # Optional: configure additional parameters
    tags: ["my_task_tag"]

work_pools:
  - name: my-docker-work-pool
    type: docker
    queues:
      - name: default
        concurrency: 10

In this example: - The task runner for the

my_flow

flow is specified as

ConcurrentTaskRunner

. - We've set an optional parameter

max_workers

to limit the number of concurrent workers. ### Resources for Further Reading - Prefect Documentation on Task Runners - Prefect Blog on Deploying Task Queues For a more detailed example and additional context, you can also refer to the code example provided here. Feel free to adjust the configurations according to your specific requirements.