[QGIS-Developer] Anyone noticed odd network behaviour while QGIS is loaded?

[Nyall Dawson]

Hey all,

I came across this thread recently
https://www.reddit.com/r/krita/comments/9xea9b/this_is_gonna_sound_crazy_but_is_krita/
, where someone reports that having Krita open was causing their wifi
connection to regularly drop out.

Long story short, it looks like this is caused by default network
scanning behaviour in the Qt library, so in theory QGIS should also be
affected by this. The typical symptom is that network ping latencies
will jump every 10 seconds while a Qt app is running.

I personally couldn't reproduce this, but the issue seems so
widespread (google for "QT_BEARER_POLL_TIMEOUT") that I'd be surprised
if QGIS wasn't affected too.

So my questions are:

1. Has anyone noticed this?
2. Should we just go ahead and apply the workaround which other Qt
applications are doing and set the environment variable
QT_BEARER_POLL_TIMEOUT=-1 by default? The side effect of this change
is that Qt's network polling would be completely disabled, so e.g.
changing from wifi to wireless while a QGIS session is open could
result in that session being unable to connect to the network
(requiring a QGIS restart)

Nyall