From cb653c5ef9e865b312da78a0c8d666ec7dd6043e Mon Sep 17 00:00:00 2001
From: Ben Darnell <ben@bendarnell.com>
Date: Sun, 1 Dec 2013 15:04:02 -0500
Subject: [PATCH] Document the attributes required by @run_on_executor.

Closes #933.
---
 tornado/concurrent.py | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/tornado/concurrent.py b/tornado/concurrent.py
index 9a10905e..a9002b16 100644
--- a/tornado/concurrent.py
+++ b/tornado/concurrent.py
@@ -151,6 +151,9 @@ def run_on_executor(fn):
 
     The decorated method may be called with a ``callback`` keyword
     argument and returns a future.
+
+    This decorator should be used only on methods of objects with attributes
+    ``executor`` and ``io_loop``.
     """
     @functools.wraps(fn)
     def wrapper(self, *args, **kwargs):