Merge pull request #190 from ericpre/fix_py38_windows

Fix for python 3.8 on windows

hyperspyui/widgets/consolewidget.py

@@ -20,6 +20,7 @@
 
 @author: Vidar Tonaas Fauske
 """
+import sys
 
 try:
  from qtconsole.rich_jupyter_widget import RichJupyterWidget
@@ -31,11 +32,42 @@
 from IPython.lib import guisupport
 
 
+def _init_asyncio_patch():
+ """set default asyncio policy to be compatible with tornado
+ Tornado 6 (at least) is not compatible with the default
+ asyncio implementation on Windows
+
+ Pick the older SelectorEventLoopPolicy on Windows
+ if the known-incompatible default policy is in use.
+ do this as early as possible to make it a low priority and overrideable
+
+ ref: https://github.com/tornadoweb/tornado/issues/2608
+ FIXME: if/when tornado supports the defaults in asyncio,
+ remove and bump tornado requirement for py38
+ """
+ if sys.platform.startswith("win") and sys.version_info >= (3, 8):
+ import asyncio
+ try:
+ from asyncio import (
+ WindowsProactorEventLoopPolicy,
+ WindowsSelectorEventLoopPolicy,
+ )
+ except ImportError:
+ pass
+ # not affected
+ else:
+ if type(asyncio.get_event_loop_policy()) is WindowsProactorEventLoopPolicy:
+ # WindowsProactorEventLoopPolicy is not compatible with tornado 6
+ # fallback to the pre-3.8 default of Selector
+ asyncio.set_event_loop_policy(WindowsSelectorEventLoopPolicy())
+
+
 class ConsoleWidget(RichJupyterWidget):
 
  def __init__(self, *args, **kwargs):
  super(ConsoleWidget, self).__init__(*args, **kwargs)
 
+ _init_asyncio_patch()
  # Create an in-process kernel
  app = guisupport.get_app_qt4()
  kernel_manager = QtInProcessKernelManager()