When does Resque open a redis connection?

I've been running into Redis::TimeoutError: Connection timed out errors on Heroku, and I'm trying to pin down the problem. I'm only using Resque to connect to redis, so I'm wondering how Resque connects to redis:

1. When does Resque connect to redis? When a worker is started?
2. How long do redis connections last, typically?

It's unclear to me when connections are made and how long they last. Can anyone shed some light on this for me? Thanks!