Intermittent bug with asyncio and MS Edge

[Chris Angelico]

On Sun, Mar 22, 2020 at 8:42 PM Frank Millman <frank at chagford.com> wrote:
>
> On 2020-03-22 11:00 AM, Barry Scott wrote:
> >
> >
> >> On 22 Mar 2020, at 07:56, Frank Millman <frank at chagford.com> wrote:
> >>
> >> On 2020-03-21 8:04 PM, Barry Scott 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!
> >
> > You can tell wireshark to only capture on one interface and to only capture packets for port 80.
> > (Captureing HTTPS means you cannot decode the packets without going deeper I recall)
> >
> > Then you can tell wireshark to decode the captured data for http to drop a lot of the lower level details.
> >
>
> Thanks. I am more or less doing that. Interestingly the [RST,ACK]
> messages appear on the tcp packets, so if I filter on http I do not see
> them.
>

I'm not 100% sure what "filter on HTTP" actually means, and it might
show only the data packets. Instead, filter on "from port 80 or to
port 80", which should show you the entire connection including the
SYN - SYN/ACK - ACK handshake, every data and acknowledgement packet,
and then whichever closing sequence gets used.

> >> 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.
> >
> > What is the async wait to wait for the transmit buffers to drain?
> >
>
> Not sure what you are asking. I am just doing what it says in the docs -
>

I think his question is "what would asyncio be sleeping for, since you
already made it wait till it was drained". And my guess is that
there's a bug somewhere; the question is where.

ChrisA