Heat is getting RPC timeouts

Issue

The following error is found in the heat-api.log when you start heat and try to access it from horizon.

2014-07-31 20:51:35.239 2234 INFO heat.api [-] Starting Heat ReST API on 0.0.0.0:8004
2014-07-31 22:23:57.301 4675 INFO keystoneclient.middleware.auth_token [-] Starting keystone auth_token middleware
2014-07-31 22:23:57.302 4675 INFO keystoneclient.middleware.auth_token [-] Using /tmp/keystone-signing-heat as cache directory for signing certificate
2014-07-31 22:23:57.304 4675 INFO heat.api [-] Starting Heat ReST API on 0.0.0.0:8004
2014-07-31 22:24:12.141 4675 INFO urllib3.connectionpool [-] Starting new HTTP connection (1): 192.168.0.1
2014-07-31 22:24:12.154 4675 INFO keystoneclient.middleware.auth_token [-] Auth Token confirmed use of v2.0 apis
2014-07-31 22:24:12.155 4675 INFO urllib3.connectionpool [-] Starting new HTTP connection (1): 192.168.0.1
2014-07-31 22:24:12.275 4675 INFO urllib3.connectionpool [-] Starting new HTTP connection (1): 192.168.0.1
2014-07-31 22:24:12.349 4675 INFO heat.openstack.common.rpc.impl_qpid [-] Connected to AMQP server on 192.168.0.1:5672
2014-07-31 22:24:12.361 4675 INFO heat.openstack.common.rpc.impl_qpid [-] Connected to AMQP server on 192.168.0.1:5672
2014-07-31 22:25:12.368 4675 ERROR root [-] Unexpected error occurred serving API: Timeout while waiting on RPC response - topic: "engine", RPC method: "list_stacks" info: "<unknown>"
2014-07-31 22:25:12.368 4675 TRACE root Traceback (most recent call last):
2014-07-31 22:25:12.368 4675 TRACE root   File "/usr/lib/python2.6/site-packages/heat/common/wsgi.py", line 677, in __call__
2014-07-31 22:25:12.368 4675 TRACE root     request, **action_args)
2014-07-31 22:25:12.368 4675 TRACE root   File "/usr/lib/python2.6/site-packages/heat/common/wsgi.py", line 745, in dispatch
2014-07-31 22:25:12.368 4675 TRACE root     return method(*args, **kwargs)
2014-07-31 22:25:12.368 4675 TRACE root   File "/usr/lib/python2.6/site-packages/heat/api/openstack/v1/util.py", line 31, in handle_stack_method
2014-07-31 22:25:12.368 4675 TRACE root     return handler(controller, req, **kwargs)
2014-07-31 22:25:12.368 4675 TRACE root   File "/usr/lib/python2.6/site-packages/heat/api/openstack/v1/stacks.py", line 186, in index
2014-07-31 22:25:12.368 4675 TRACE root     stacks = self.engine.list_stacks(req.context)
2014-07-31 22:25:12.368 4675 TRACE root   File "/usr/lib/python2.6/site-packages/heat/rpc/client.py", line 59, in list_stacks
2014-07-31 22:25:12.368 4675 TRACE root     return self.call(ctxt, self.make_msg('list_stacks'))
2014-07-31 22:25:12.368 4675 TRACE root   File "/usr/lib/python2.6/site-packages/heat/openstack/common/rpc/proxy.py", line 130, in call
2014-07-31 22:25:12.368 4675 TRACE root     exc.info, real_topic, msg.get('method'))
2014-07-31 22:25:12.368 4675 TRACE root Timeout: Timeout while waiting on RPC response - topic: "engine", RPC method: "list_stacks" info: "<unknown>"
2014-07-31 22:25:12.368 4675 TRACE root