Canceling workflows and start_delay

Community Support
1

I am wondering on how cancelation is handled in the case of a start_delay.
If I understand correctly if I send a cancelation to an actively running workflow it will add a WorkflowExecutionCancelRequested event and if I don’t handle it, the workflow won’t actually stop running.
But what happens in the case of a start_delay, do I still need to explicitly handle the WorkflowExecutionCancelRequested event?

can I get a code example of how cancelation is properly handled in a workflow?

2

The server will schedule a workflow task to dispatch the cancelation request. You can test it adding the delay here and run the example

If I understand correctly if I send a cancelation to an actively running workflow it will add a WorkflowExecutionCancelRequested event and if I don’t handle it, the workflow won’t actually stop running.

In Python if you handle the cancelation request (eg ignore the CancelledError thrown by the activity) the workflow won’t be cancelled

3

Sorry I am not sure I understand lets say have a workflow I start like this

handle = await self._temporal_client.start_workflow(
   CreateVmWorkflow.run,
   workflow_args,
   id=workflow_id,
   task_queue="service-queue",
   search_attributes=search_attributes,
   start_delay=start_time - now(tz="UTC"),
)

so it’s starting in the future. I changed my mind and I don’t want this workflow to run so I do later

await handle.cancel()

if the workflows doesn’t have a:

try:
    ...
except CancelledError as e:
   cleanup()

then the workflow will not actually be canceled? is this also true with the start_delay=start_time - now(tz="UTC") above?
Also let’s say I do have a the try / except block in the workflow, when will the CancelledError be processed? like will the start_delay-ed workflow still be marked as running until the start time or will it immediately handle the exception?