Start a task/process when a job gets in and only stop it when jobs stop comming in

[arthur-er]

I'm building a service where each user can open a long-running task (think of a web scrapper), the users can insert many jobs into the queue, but generally do this in batches, how I can keep a processor "hot" for the user, so when he send subsequent jobs it is already open, and close it after a delay in the jobs sending