Intermittent bug with asyncio and MS Edge

[Chris Angelico]

On Sun, Mar 22, 2020 at 12:45 AM Frank Millman <frank at chagford.com> wrote:
>
> Hi all
>
> I have a strange intermittent bug.
>
> The role-players -
>      asyncio on Python 3.8 running on Windows 10
>      Microsoft Edge running as a browser on the same machine
>
> The bug does not occur with Python 3.7.
> It does not occur with Chrome or Firefox.
> It does not occur when MS Edge connects to another host on the network,
> running the same Python program (Python 3.8 on Fedora 31).

What exact version of Python 3.7 did you test? I'm looking through the
changes to asyncio and came across this one, which may have some
impact.

https://bugs.python.org/issue36801

Also this one made a change that introduced a regression that was
subsequently fixed. Could be interesting.

https://bugs.python.org/issue36802

What happens if you try awaiting your writes? I think it probably
won't make any difference, though - from my reading of the source, I
believe that "await writer.write(...)" is the same as
"writer.write(...); await writer.drain()", so it's going to be exactly
the same as you're already doing.

ChrisA