Clear the loop variable in addition to the callback list.

Closes #844.

diff --git a/tornado/ioloop.py b/tornado/ioloop.py
index 49e37eb9516f2ec16c44167889925cfb71de4296..fe7e276d5f2999c76fd53a995b11430cb7ddfd20 100644 (file)
--- a/tornado/ioloop.py
+++ b/tornado/ioloop.py
@@ -607,7 +607,7 @@ class PollIOLoop(IOLoop):
                 self._run_callback(callback)
             # Closures may be holding on to a lot of memory, so allow
             # them to be freed before we go into our poll wait.
-            del callbacks
+            callbacks = callback = None
 
             if self._timeouts:
                 now = self.time()