Manual Slot Release

The Hatchet execution model sets a number of available slots for running tasks in a workflow. When a task is running, it occupies a slot, and if a worker has no available slots, it will not be able to run any more tasks concurrently.

In some cases, you may have a task in your workflow that is resource-intensive and requires exclusive access to a shared resource, such as a database connection or a GPU compute instance. To ensure that other tasks in the workflow can run concurrently, you can manually release the slot after the resource-intensive task has completed, but the task still has non-resource-intensive work to do (i.e. upload or cleanup).

Using Manual Slot Release

You can manually release a slot in from within a running task in your workflow using the Hatchet context method release_slot:

slot_release_workflow = hatchet.workflow(name="SlotReleaseWorkflow")


@slot_release_workflow.task()
def step1(input: EmptyModel, ctx: Context) -> dict[str, str]:
    print("RESOURCE INTENSIVE PROCESS")
    time.sleep(10)

    ctx.release_slot()

    print("NON RESOURCE INTENSIVE PROCESS")
    return {"status": "success"}

🚨 No snippet found for SlotRelease 

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func StepOne(ctx worker.HatchetContext) (result \*taskOneOutput, err error) {
  fmt.Println("RESOURCE INTENSIVE PROCESS")
  time.Sleep(10 * time.Second)
  // Release the slot after the resource-intensive process, so that other tasks can run
  ctx.ReleaseSlot()
  fmt.Println("NON RESOURCE INTENSIVE PROCESS")
  return &taskOneOutput{
    Message: "task1 results",
  }, nil
},

In the above examples, the release_slot() method is called after the resource-intensive process has completed. This allows other tasks in the workflow to start executing while the current task continues with non-resource-intensive tasks.

Use Cases

Some common use cases for Manual Slot Release include:

• Performing data processing or analysis that requires significant CPU, GPU, or memory resources
• Acquiring locks or semaphores to access shared resources
• Executing long-running tasks that don’t need to block other tasks after some initial work is done

By utilizing Manual Slot Release, you can optimize the concurrency and resource utilization of your workflows, allowing multiple tasks to run in parallel when possible.