Intermittent bug with asyncio and MS Edge
Frank Millman
frank at chagford.com
Sun Mar 22 03:56:29 EDT 2020
On 2020-03-21 8:04 PM, Barry Scott wrote:
>
>
>> On 21 Mar 2020, at 13:43, 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).
>>
>> The symptoms -
>> On receiving a connection, I send an HTML page to the browser,
>> which has 20 lines like this -
>>
>> <script type="text/javascript" src="src/main.js"></script>
>> <script type="text/javascript" src="src/on_load.js"></script>
>> ...
>>
>> Intermittently, one or other of the script files is not received by MS Edge.
>>
[...]
>> >> I don't know whether the problem lies with Python or MS Edge, but as
it does not happen with Python 3.7, I am suspecting that something
changed in 3.8 which does not match MS Edge's expectations.
>
> 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.
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.
I will keep digging, but I thought I would post this information now in
case it helps with diagnosis.
Frank
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