From 9832ac6ffd861e92d4054c38943b3c2c00ea5a2f 2011-05-08 15:14:54
From: epatters <epatters@enthought.com>
Date: 2011-05-08 15:14:54
Subject: [PATCH] Fix serious bug in heartbeat logic that can result in no-timeout polls.

---

diff --git a/IPython/zmq/kernelmanager.py b/IPython/zmq/kernelmanager.py
index 4b30621..3656157 100644
--- a/IPython/zmq/kernelmanager.py
+++ b/IPython/zmq/kernelmanager.py
@@ -573,7 +573,8 @@ class HBSocketChannel(ZmqSocketChannel):
                                 # list, poll is working correctly even if it
                                 # returns quickly. Note: poll timeout is in
                                 # milliseconds.
-                                self.poller.poll(1000*until_dead)
+                                if until_dead > 0.0:
+                                    self.poller.poll(1000 * until_dead)
                             
                                 since_last_heartbeat = time.time()-request_time
                                 if since_last_heartbeat > self.time_to_dead: