任务并行库替换 Background Worker? ？

Background worker is still a valid way of achieving this - if you are running multiple large operations concurrently then the parallel extensions would be worth considering, if its just the one then I would stick with the backgroundworker.

The Task class is an improvement over the BackgroundWorker; it naturally supports nesting (parent/child tasks), uses the new cancellation API, task continuations, etc.

I have an example on my blog, showing the old BackgroundWorker way of doing things and the new Task way of doing things. I do have a small helper class for tasks that need to report progress, because I find the syntax rather awkward. The example covers result values, error conditions, cancellation, and progress reporting.