Retrieve, view results, and cancel futures using client

Question

Scenario: User A connects to dask scheduler, sends a long job using client.map(func, list) and logs off for the weekend. User B wants to view the results of the finished Futures created by User A and possibly cancel the pending futures.

We managed to get the results of futures present in the workers as follows:

from dask.distributed import Client
from distributed.client import Future

client = Client("tcp://scheduler_ip:8786")
for worker, futures in client.has_what().items():
    for future_id in futures:
        f = Future(future_id, client)
        f._state.status = "finished"
        print(f.result())

Doing an f.cancel() does nothing. Is there a way to achieve this?

Answer 1

Share futures

You might consider sharing futures using constructs like Variables and Queues. See these docs for more information.

Cancel futures

Cancel will stop a task if it hasn't yet started. Unfortunately, once a function has started running there is no way to stop it short of killing that worker.