Check if a task with a specific description is already running

I hate to be that guy, but to me this looks like the wrong way to go about things. If you have an issue with jobs stepping on each other's toes, something went wrong when defining those jobs. This is why Workflow Profiles, for example, enforce entity separation. I'd try to determine why "contention" happens and stop that from happening in the first place. Trying to kill jobs will result in more problems down the line.