The external worker will keep polling / checking for new task in the topic it has subscribed to until it is stopped.
There are parameters to help control the check frequency, how many task are fetched at once, long polling (how long to wait for a task in each blocking call) , and even how the frequency changes if there are no work items. These parameters help avoid unnecessary network traffic during idle times or bothering the server with too many requests.
You can terminate the worker with Ctrl-C.