How to fetch multiple feeds concurrently

I am new to ruby on rails and I have just started watching rails casts tutorials.

To parse feeds, I have started using feed zirra.

To fetch multiple feeds at once, feedzirra has this feature

feed_urls = ["http://feeds.feedburner.com/PaulDixExplainsNothing",
"http://feeds.feedburner.com/trottercashion"]
feeds = Feedzirra::Feed.fetch_and_parse(feed_urls)

If I have 100 feeds, this procedure takes some time to index the 100th feed so,

How to parse fetch all these lets say 100 feeds concurrently?

Looking forward for your help and support