From: Ben Darnell <ben@bendarnell.com>
Date: Sun, 27 Sep 2015 22:09:16 +0000 (-0400)
Subject: Document interactions with TornadoReactor and multi-process.
X-Git-Tag: v4.3.0b1~32
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=9ebfc397546365123210b10ef86035236dcb5bd8;p=thirdparty%2Ftornado.git

Document interactions with TornadoReactor and multi-process.

See #1501.
---

diff --git a/tornado/platform/twisted.py b/tornado/platform/twisted.py
index 827e3bd2c..d3a4e75d1 100644
--- a/tornado/platform/twisted.py
+++ b/tornado/platform/twisted.py
@@ -339,8 +339,17 @@ class _TestReactor(TornadoReactor):
 def install(io_loop=None):
     """Install this package as the default Twisted reactor.
 
+    ``install()`` must be called very early in the startup process,
+    before most other twisted-related imports. Conversely, because it
+    initializes the `.IOLoop`, it cannot be called before
+    `.fork_processes` or multi-process `~.TCPServer.start`. These
+    conflicting requirements make it difficult to use `.TornadoReactor`
+    in multi-process mode, and an external process manager such as
+    ``supervisord`` is recommended instead.
+
     .. versionchanged:: 4.1
        The ``io_loop`` argument is deprecated.
+
     """
     if not io_loop:
         io_loop = tornado.ioloop.IOLoop.current()