[Qgis-user] Qgis crashes while loading WMTS layers

[Jonathan Moules]

Hi Patrick,

I'd suggest reporting this to the QGIS bug tracker as a regression.

Cheers,

Jonathan

On 2020-02-01 07:20, Patrick Dunford wrote:
> Further investigation and comment
>
> Since recently installing Qgis 3.4.15 or 3.4.14 on some of my 
> computers running Debian 10, I immediately began to see a trend of the 
> software exhibiting an increased tendency to crash when working with 
> certain WMTS layers that I had previously worked with extensively over 
> recent weeks for mapping purposes.
>
> After attempting numerous changes including special versions of 
> projects containing no file based raster layers and only containing 
> one WMTS layer at a time and being unable to use the software 
> regardless I created a virtual machine running Debian 9 which has the 
> latest version available for that platform, 3.4.4. This has resulted 
> in immediate major improvement in the reliability of the software to 
> the point I can resume using it without the numerous crashes of the 
> software that have been noted recently, especially in the last week 
> approximately.
>
> On 27/01/20 1:19 am, Patrick Dunford wrote:
>> 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.
>>
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