queue: Disable RabbitMQ heartbeat in BlockingConnection.

Fixes #741.

zerver/lib/queue.py

@@ -23,6 +23,8 @@ class SimpleQueueClient(object):
         self.queues = set() # type: Set[str]
         self.channel = None # type: Any
         self.consumers = defaultdict(set) # type: Dict[str, Set[Any]]
+        # Disable RabbitMQ heartbeats since BlockingConnection can't process them
+        self.rabbitmq_heartbeat = 0
         self._connect()
 
     def _connect(self):
@@ -38,9 +40,12 @@ class SimpleQueueClient(object):
         self._connect()
 
     def _get_parameters(self):
+        # We explicitly disable the RabbitMQ heartbeat feature, since
+        # it doesn't make sense with BlockingConnection
         credentials = pika.PlainCredentials(settings.RABBITMQ_USERNAME,
                                             settings.RABBITMQ_PASSWORD)
         return pika.ConnectionParameters(settings.RABBITMQ_HOST,
+                                         heartbeat_interval=self.rabbitmq_heartbeat,
                                          credentials=credentials)
 
     def _generate_ctag(self, queue_name):
@@ -158,6 +163,8 @@ class TornadoQueueClient(SimpleQueueClient):
     # https://pika.readthedocs.io/en/0.9.8/examples/asynchronous_consumer_example.html
     def __init__(self):
         super(TornadoQueueClient, self).__init__()
+        # Enable rabbitmq heartbeat since TornadoConection can process them
+        self.rabbitmq_heartbeat = None
         self._on_open_cbs = [] # type: List[Callable[[], None]]
 
     def _connect(self, on_open_cb = None):