From 370078020f69eed123a42f988b647d9b2fbd418a Mon Sep 17 00:00:00 2001
From: MinRK <benjaminrk@gmail.com>
Date: Mon, 23 Jan 2012 13:40:01 -0800
Subject: [PATCH] flush outgoing heartbeats

Prevents mismatch between heartbeat timer and actual heartbeat send/recv events.

Applied in notebook and parallel.
---
 IPython/frontend/html/notebook/handlers.py | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/IPython/frontend/html/notebook/handlers.py b/IPython/frontend/html/notebook/handlers.py
index 9a37c4372..304f05c6a 100644
--- a/IPython/frontend/html/notebook/handlers.py
+++ b/IPython/frontend/html/notebook/handlers.py
@@ -481,6 +481,8 @@ class IOPubHandler(AuthenticatedZMQStreamHandler):
                 if self._kernel_alive:
                     self._kernel_alive = False
                     self.hb_stream.send(b'ping')
+                    # flush stream to force immediate socket send
+                    self.hb_stream.flush()
                 else:
                     try:
                         callback()