From 317508b7b538aca59a883809456e98e3dbd237e6 Mon Sep 17 00:00:00 2001
From: Peter Sobot <github@petersobot.com>
Date: Tue, 23 Oct 2012 18:06:08 -0300
Subject: [PATCH] Added more sensical callback time verification.

---
 tornado/ioloop.py | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/tornado/ioloop.py b/tornado/ioloop.py
index dfbb462b..5f01223b 100644
--- a/tornado/ioloop.py
+++ b/tornado/ioloop.py
@@ -679,8 +679,8 @@ class PeriodicCallback(object):
     """
     def __init__(self, callback, callback_time, io_loop=None):
         self.callback = callback
-        if callback_time == 0:
-            raise ValueError("Periodic callback cannot have a period of 0ms")
+        if callback_time <= 0:
+            raise ValueError("Periodic callback must have a positive callback_time")
         self.callback_time = callback_time
         self.io_loop = io_loop or IOLoop.instance()
         self._running = False