Thumbnailing every single image file slows the MTP connection down

[wanderer1988]

I hope I report this issue here on the right package. I have reported it also on together.jolla.com

As far as I understand, the MTP stack tries to create a thumbnail for every Image file on the storage, which is visible via the MTP connection. This is a terribly bad solution if you have a huge amount of images in the internal storage, because that fills up the thumbnail storage to the limit and causes MTP connection to malfunction.

In practice this happens especially, if you are using a Map application, which stores all the map tiles on the storage. I experienced this issue with the app "modrana" on my Jolla phone, which stores all the downloaded map tiles as pngs in ~/.local/share/harbour-modrana/maps. I had over 83000 files in it. Because of this, establishing an MTP connection with a PC became very sluggish and sometimes even didn't work at all. When I ran msyncd directly on the command line I got thousands of outputs like

[W] meegomtp1dot0::Thumbnailer::slotError:107 - Thumbnailer returned error for::  "file:///home/nemo/.local/share/harbour-modrana/maps/mapquest_eu/18/142193/91765.png"

The thumbnails are stored in the folder ~/.thumbnails. I deleted all the files in it and tried to make an MTP connection again afterwards. In this situation msyncd outputs

[W] meegomtp1dot0::Thumbnailer::recordRequest:141 - Thumbnailer::Exceeded max req size!

a few hundred times. Looks like if the thumbnail storage exceeds the upper limit.