RabbitMQ supports priorities now. Closes #2835

docs/faq.rst

@@ -746,13 +746,15 @@ create a new schedule subclass and override
 Does celery support task priorities?
 ------------------------------------
 
-**Answer**: No. In theory, yes, as AMQP supports priorities. However
-RabbitMQ doesn't implement them yet.
+**Answer**: Yes.
 
-The usual way to prioritize work in Celery, is to route high priority tasks
-to different servers. In the real world this may actually work better than per message
-priorities. You can use this in combination with rate limiting to achieve a
-highly responsive system.
+RabbitMQ supports priorities since version 3.5.0.
+Redis transport emulates support of priorities.
+
+You can also prioritize work by routing high priority tasks
+to different workers.  In the real world this may actually work better
+than per message priorities.  You can use this in combination with rate
+limiting to achieve a responsive system.
 
 .. _faq-acks_late-vs-retry:
 

docs/getting-started/next-steps.rst

@@ -122,7 +122,7 @@ the :ref:`Monitoring and Management guide <guide-monitoring>`.
 tasks from.  The worker can be told to consume from several queues
 at once, and this is used to route messages to specific workers
 as a means for Quality of Service, separation of concerns,
-and emulating priorities, all described in the :ref:`Routing Guide
+and prioritization, all described in the :ref:`Routing Guide
 <guide-routing>`.
 
 You can get a complete list of command-line arguments

docs/userguide/calling.rst

@@ -497,6 +497,6 @@ AMQP's full routing capabilities. Interested parties may read the
 
 - priority
 
-    A number between `0` and `9`, where `0` is the highest priority.
+    A number between `0` and `255`, where `255` is the highest priority.
 
-    Supported by: redis, beanstalk
+    Supported by: rabbitmq, redis (priority reversed, 0 is highest), beanstalk