diff --git a/eventlet/hubs/hub.py b/eventlet/hubs/hub.py
index ba48cdb..2fee198 100644
--- a/eventlet/hubs/hub.py
+++ b/eventlet/hubs/hub.py
@@ -26,9 +26,14 @@ class FdListener(object):
 class DebugListener(FdListener):
     def __init__(self, evtype, fileno, cb):
         self.where_called = traceback.format_stack()
+        self.greenlet = greenlet.getcurrent()
         super(DebugListener, self).__init__(evtype, fileno, cb)
     def __repr__(self):
-        return "DebugListener(%r, %r, %r)\n%sEndDebugFdListener" % (self.evtype, self.fileno, self.cb, ''.join(self.where_called))
+        return "DebugListener(%r, %r, %r, %r)\n%sEndDebugFdListener" % (self.evtype,
+                                                                        self.fileno,
+                                                                        self.cb,
+                                                                        self.greenlet,
+                                                                        ''.join(self.where_called))
     __str__ = __repr__
     
 
diff --git a/eventlet/hubs/poll.py b/eventlet/hubs/poll.py
index 2a38621..ab214f4 100644
--- a/eventlet/hubs/poll.py
+++ b/eventlet/hubs/poll.py
@@ -23,8 +23,8 @@ class Hub(BaseHub):
             self.modify = self.poll.register
 
     def add(self, evtype, fileno, cb):
-        oldlisteners = bool(self.listeners[evtype].get(fileno))
-
+        oldlisteners = bool(self.listeners[READ].get(fileno) or
+                            self.listeners[WRITE].get(fileno))
         listener = super(Hub, self).add(evtype, fileno, cb)
         if not oldlisteners:
             # Means we've added a new listener
diff --git a/eventlet/tpool.py b/eventlet/tpool.py
index da619bd..8b82b19 100644
--- a/eventlet/tpool.py
+++ b/eventlet/tpool.py
@@ -19,7 +19,6 @@ import sys
 
 from Queue import Empty, Queue
 
-from eventlet import api
 from eventlet import event
 from eventlet import greenio
 from eventlet import greenthread
@@ -234,8 +233,8 @@ def killall():
     for thr in _threads.values():
         thr.join()
     _threads.clear()
-    if _coro:
-        api.kill(_coro)
+    if _coro is not None:
+        greenthread.kill(_coro)
     _rfile.close()
     _wfile.close()
     _rfile = None
diff --git a/tests/__init__.py b/tests/__init__.py
index 26d0406..ea2460c 100644
--- a/tests/__init__.py
+++ b/tests/__init__.py
@@ -106,6 +106,15 @@ class LimitedTestCase(unittest.TestCase):
         self.timer.cancel()
 
 
+def verify_hub_empty():
+    from eventlet import hubs
+    hub = hubs.get_hub()
+    num_readers = len(hub.get_readers())
+    num_writers = len(hub.get_writers())
+    num_timers = len(hub.get_timers_count())
+    assert num_readers == 0 and num_writers == 0, "Readers: %s Writers: %s" % (num_readers, num_writers)
+
+
 def find_command(command):
     for dir in os.getenv('PATH', '/usr/bin:/usr/sbin').split(os.pathsep):
         p = os.path.join(dir, command)