diff --git a/nova/rpc.py b/nova/rpc.py
index 493978e57e0a..1ec495bc890e 100644
--- a/nova/rpc.py
+++ b/nova/rpc.py
@@ -28,6 +28,7 @@ import json
 import sys
 import time
 import traceback
+import types
 import uuid
 
 from carrot import connection as carrot_connection
@@ -228,7 +229,7 @@ class AdapterConsumer(Consumer):
             rval = node_func(context=ctxt, **node_args)
             if msg_id:
                 # Check if the result was a generator
-                if hasattr(rval, 'send'):
+                if isinstance(rval, types.GeneratorType):
                     for x in rval:
                         msg_reply(msg_id, x, None)
                 else:
@@ -236,7 +237,7 @@ class AdapterConsumer(Consumer):
 
                 # This final None tells multicall that it is done.
                 msg_reply(msg_id, None, None)
-            elif hasattr(rval, 'send'):
+            elif isinstance(rval, types.GeneratorType):
                 # NOTE(vish): this iterates through the generator
                 list(rval)
         except Exception as e:
@@ -281,11 +282,11 @@ class FanoutAdapterConsumer(AdapterConsumer):
 class ConsumerSet(object):
     """Groups consumers to listen on together on a single connection."""
 
-    def __init__(self, conn, consumer_list):
+    def __init__(self, connection, consumer_list):
         self.consumer_list = set(consumer_list)
         self.consumer_set = None
         self.enabled = True
-        self.init(conn)
+        self.init(connection)
 
     def init(self, conn):
         if not conn:
@@ -316,8 +317,7 @@ class ConsumerSet(object):
                     running = False
                     break
                 except Exception as e:
-                    LOG.error(_("Received exception %s " % type(e) + \
-                            "while processing consumer"))
+                    LOG.exception(_("Exception while processing consumer"))
                     self.reconnect()
                     # Break to outer loop
                     break
@@ -534,7 +534,10 @@ def call(context, topic, msg):
     """Sends a message on a topic and wait for a response."""
     rv = multicall(context, topic, msg)
     # NOTE(vish): return the last result from the multicall
-    return list(rv)[-1]
+    rv = list(rv)
+    if not rv:
+        return
+    return rv[-1]
 
 
 def cast(context, topic, msg):
diff --git a/nova/service.py b/nova/service.py
index 7821833227c0..74f9f04d85bf 100644
--- a/nova/service.py
+++ b/nova/service.py
@@ -105,19 +105,18 @@ class Service(object):
                 connection=self.conn,
                 topic=self.topic,
                 proxy=self)
-
-        cset = rpc.ConsumerSet(self.conn, [consumer_all,
-                                           consumer_node,
-                                           fanout])
+        consumer_set = rpc.ConsumerSet(
+                connection=self.conn,
+                consumer_list=[consumer_all, consumer_node, fanout])
 
         # Wait forever, processing these consumers
         def _wait():
             try:
-                cset.wait()
+                consumer_set.wait()
             finally:
-                cset.close()
+                consumer_set.close()
 
-        self.csetthread = greenthread.spawn(_wait)
+        self.consumer_set_thread = greenthread.spawn(_wait)
 
         if self.report_interval:
             pulse = utils.LoopingCall(self.report_state)
@@ -182,9 +181,9 @@ class Service(object):
             logging.warn(_('Service killed that has no database entry'))
 
     def stop(self):
-        self.csetthread.kill()
+        self.consumer_set_thread.kill()
         try:
-            self.csetthread.wait()
+            self.consumer_set_thread.wait()
         except greenlet.GreenletExit:
             pass
         for x in self.timers:
diff --git a/nova/tests/test_rpc.py b/nova/tests/test_rpc.py
index 35f4a64d97e9..ffd748efe540 100644
--- a/nova/tests/test_rpc.py
+++ b/nova/tests/test_rpc.py
@@ -66,12 +66,10 @@ class RpcTestCase(test.TestCase):
                               'test',
                               {"method": "echo",
                                "args": {"value": value}})
-        i = 0
-        for x in result:
+        for i, x in enumerate(result):
             if i > 0:
                 self.fail('should only receive one response')
             self.assertEqual(value + i, x)
-            i += 1
 
     def test_multicall_succeed_three_times(self):
         value = 42
@@ -79,10 +77,8 @@ class RpcTestCase(test.TestCase):
                               'test',
                               {"method": "echo_three_times",
                                "args": {"value": value}})
-        i = 0
-        for x in result:
+        for i, x in enumerate(result):
             self.assertEqual(value + i, x)
-            i += 1
 
     def test_multicall_succeed_three_times_yield(self):
         value = 42
@@ -90,10 +86,8 @@ class RpcTestCase(test.TestCase):
                               'test',
                               {"method": "echo_three_times_yield",
                                "args": {"value": value}})
-        i = 0
-        for x in result:
+        for i, x in enumerate(result):
             self.assertEqual(value + i, x)
-            i += 1
 
     def test_context_passed(self):
         """Makes sure a context is passed through rpc call."""
diff --git a/nova/tests/test_service.py b/nova/tests/test_service.py
index 0bba01d921ef..d1cc8bd61a1a 100644
--- a/nova/tests/test_service.py
+++ b/nova/tests/test_service.py
@@ -142,7 +142,8 @@ class ServiceTestCase(test.TestCase):
 
         mock_cset = self.mox.CreateMock(rpc.ConsumerSet,
                 {'wait': wait_func})
-        rpc.ConsumerSet(mox.IgnoreArg(), mox.IsA(list)).AndReturn(mock_cset)
+        rpc.ConsumerSet(connection=mox.IgnoreArg(),
+                        consumer_list=mox.IsA(list)).AndReturn(mock_cset)
         wait_func(mox.IgnoreArg())
 
         service_create = {'host': host,
@@ -331,7 +332,8 @@ class ServiceTestCase(test.TestCase):
 
         mock_cset = self.mox.CreateMock(rpc.ConsumerSet,
                 {'wait': wait_func})
-        rpc.ConsumerSet(mox.IgnoreArg(), mox.IsA(list)).AndReturn(mock_cset)
+        rpc.ConsumerSet(connection=mox.IgnoreArg(),
+                        consumer_list=mox.IsA(list)).AndReturn(mock_cset)
         wait_func(mox.IgnoreArg())
 
         self.mox.StubOutWithMock(serv.manager.driver,