From aa879d1934e36fd81f49535cd3a1d5bc60b0e044 Mon Sep 17 00:00:00 2001 From: Ben Darnell Date: Sat, 22 Jun 2019 14:39:38 -0400 Subject: [PATCH] docs: Add notice about WindowsSelectorEventLoop on py38 Fixes #2608 --- docs/index.rst | 7 +++++++ 1 file changed, 7 insertions(+) diff --git a/docs/index.rst b/docs/index.rst index 6d2e1d73c..135fd099e 100644 --- a/docs/index.rst +++ b/docs/index.rst @@ -120,6 +120,13 @@ is limited (Even though Tornado is built on ``asyncio``, which supports Windows, Tornado does not use the APIs that are necessary for scalable networking on Windows). +On Windows, Tornado requires the ``WindowsSelectorEventLoop``. This is +the default in Python 3.7 and older, but Python 3.8 defaults to an +event loop that is not compatible with Tornado. Applications that use +Tornado on Windows with Python 3.8 must call +``asyncio.set_event_loop_policy(asyncio.WindowsSelectorEventLoopPolicy())`` +at the beginning of their ``main`` file/function. + Documentation ------------- -- 2.47.2