Welcome to Sidekiq 4.0! Sidekiq 4.0 contains a redesigned, more efficient core with less overhead per job. See my blog for an overview of Sidekiq 4's higher performance. What's New Sidekiq no longer uses Celluloid. If your application code uses Celluloid, you will need to pull it in yourself. redis-namespace has been removed from Sidekiq's gem dependencies. If you want to use namespacing (and I st