Intermittent bug with asyncio and MS Edge

[Chris Angelico]

On Sun, Mar 22, 2020 at 6:58 PM Frank Millman <frank at chagford.com> wrote:
> > I'd look at the network traffic with wireshark to see if there is anything different between edge and the other browsers.
> >
>
> You are leading me into deep waters here :-)  I have never used
> Wireshark before. I have now downloaded it and am running it - it
> generates a *lot* of data, most of which I do not understand yet!
>
> One thing immediately stands out. When I run it with MS Edge and
> Python3.8, it shows a lot of lines highlighted in red, with the symbols
> [RST,ACK]. They do not appear when running Chrome, and they do not
> appear when running Python3.7.

Interesting. RST means "Reset" and is sent when the connection is
closed. Which direction were these packets sent (Edge to Python or
Python to Edge)? You can tell by the source and destination ports -
one of them is going to be the port Python is listening on (eg 80 or
443), so if the destination port is 80, it's being sent *to* Python,
and if the source port is 80, it's being sent *from* Python.

> I have another data point. I tried putting an asyncio.sleep() after
> sending each file. A value of 0.01 made no difference, but a value of
> 0.1 makes the problem go away.

Interesting also.

Can you recreate the problem without Edge? It sounds like something's
going on with concurrent transfers, so it'd be awesome if you can
replace Edge with another Python program, and then post both programs.

Also of interest: Does the problem go away if you change "Connection:
Keep-Alive" to "Connection: Close" in your headers?

ChrisA