[QGIS-Developer] Qgis crashes while loading WMTS layers

[Patrick Dunford]

Good day to all.

Not so long ago I wrote a post about issues handling large numbers of 
raster files. This results from what appears to be an architectural 
design limitation of Qgis in that it only has enough resources available 
for a certain (unknown) number of raster layers and does not have any 
effective system for dealing with the exhaustion of these resources.

I also noted that the software does not appear to have the ability to 
use the swap (virtual memory) resources within a system to deal with the 
apparent exhaustion of resources, as other software would. For example, 
Gimp which I use for graphical editing is able to handle certain 
projects using a swap space of 200 GB, which consists of 32 GB of 
physical RAM and the rest in SSD. It is not unusual with some of these 
graphics projects to have 100 GB or more of swap space in use, without 
crashing the system. (This being possible since Gimp 2.10 with its 
ability to write files of more than 4 GB)

Whilst it is possible to manage the number of layers with file based 
rasters, this cannot be done with a WMTS server because there is no way 
I am aware of to manage the number of layers that can be downloaded from 
the server.

Version 2.18 and earlier almost never crashed with excess layers, 
usually all that would happen is a layer would be displayed with invalid 
data. However, crashes have become the norm with 3.x versions of software.

It seems to me there is a big architectural problem in the software with 
its inability to utilise the full resources of the system in order to 
process the number of layers that a WMTS server is capable of issuing.