Added pausing to the heartbeat channel.

IPython/zmq/kernelmanager.py

@@ -515,10 +515,13 b' class HBSocketChannel(ZmqSocketChannel):'
     time_to_dead = 3.0
     socket = None
     poller = None
+    _running = None
+    _pause = None
 
     def __init__(self, context, session, address):
         super(HBSocketChannel, self).__init__(context, session, address)
         self._running = False
+        self._pause = False
 
     def _create_socket(self):
         self.socket = self.context.socket(zmq.REQ)
@@ -538,6 +541,9 b' class HBSocketChannel(ZmqSocketChannel):'
         # after the sockets are connected.
         time.sleep(2.0)
         while self._running:
+            if self._pause:
+                time.sleep(self.time_to_dead)
+            else:
             since_last_heartbeat = 0.0
             request_time = time.time()
             try:
@@ -584,6 +590,21 b' class HBSocketChannel(ZmqSocketChannel):'
                             time.sleep(until_dead)
                         break
 
+    def pause(self):
+        """Pause the heartbeat."""
+        self._pause = True
+
+    def unpause(self):
+        """Unpause the heartbeat."""
+        self._pause = False
+
+    def is_beating(self):
+        """Is the heartbeat running and not paused."""
+        if self.is_alive() and not self._pause:
+            return True
+        else:
+            return False
+
     def stop(self):
         self._running = False
         super(HBSocketChannel, self).stop()
@@ -646,8 +667,8 b' class KernelManager(HasTraits):'
     # Channel management methods:
     #--------------------------------------------------------------------------
 
-    def start_channels(self, xreq=True, sub=True, rep=True, hb=True):
-        """Starts the channels for this kernel.
+    def start_channels(self, xreq=True, sub=True, rep=True):
+        """Starts the channels for this kernel, but not the heartbeat.
 
         This will create the channels if they do not exist and then start
         them. If port numbers of 0 are being used (random ports) then you
@@ -660,8 +681,6 b' class KernelManager(HasTraits):'
             self.sub_channel.start()
         if rep:
             self.rep_channel.start()
-        if hb:
-            self.hb_channel.start()
 
     def stop_channels(self):
         """Stops all the running channels for this kernel.
@@ -672,16 +691,13 b' class KernelManager(HasTraits):'
             self.sub_channel.stop()
         if self.rep_channel.is_alive():
             self.rep_channel.stop()
-        if self.hb_channel.is_alive():
-            self.hb_channel.stop()
 
     @property
     def channels_running(self):
         """Are any of the channels created and running?"""
         return self.xreq_channel.is_alive() \
             or self.sub_channel.is_alive() \
-            or self.rep_channel.is_alive() \
-            or self.hb_channel.is_alive()
+            or self.rep_channel.is_alive()
 
     #--------------------------------------------------------------------------
     # Kernel process management methods: