SimpleQueueClient was not thread-safe as the pika method
calls that we are using might disconnect and end up in a bad
state if two threads enqueue messages at the same time.
In order to avoid this, each user of the rabbitmq queue
gets its own instance of a SimpleQueueClient.
(imported from commit 694083b75cd58a60b8de282a8f40eb92a864c5ce)
Code like this is dangerous:
class SimpleQueue(object):
queues = set()
because all instances will share the same 'queues' set object.
We don't really need multiple instances, but neither is there a reason to break
them. So do the normal Python thing instead.
(imported from commit a56bb8414dd549cfd312c9565df198cf9d20f08a)
Before this is deployed, we need to install rabbitmq and pika on the
target server (see the puppet part of this commit for how).
When this is deployed, we need to start the new user activity bot:
./manage.py process_user_activity
in the screen session on the relevant server, or user_activity logs
won't be processed (which will eventually result in all users getting
notifications about how their mirrors are out of date).
(imported from commit 44d605aca0290bef2c94fb99267e15e26b21673b)
