If there were none. There is the idea replacement for RabbitMQ Gearman.
Not know Gearman, RabbitMQ well. The main difference is that in Gearman you have the option to obtain the status of a specific task at any time. In RabbitMQ, if you want to use it as a task server, this information have to be stored separately (for example, I store the progress in Radis). In addition will have to resort to "military tricks" if you want to defer processing of a job. Otherwise RabbitMQ ten times faster than Gearman, and fine scales.