[Lizmap] Thanks and question about the warning with increased number of layers

[Etienne Trimaille]

Hi Günter,

On 19/01/2024 12:59, G. Wagner, Wagner-IT via Lizmap wrote:
>
> Hi,
>
> Firstly, many thanks to the entire Lizmap development team for the 
> very active further development of the client.
>
Thanks a lot for your positive feedbacks. It's really appreciated ! Your 
message has been forwarded to the team ;-)

In open source, we don't know too much our users, and sometimes, we 
don't have too many feedbacks when it's working nicely :) (but we have 
bug reports on GitHub... :) )

We spent indeed a lot of times for releasing Lizmap Web Client 3.7 
(polish, bugfix etc), we are glad we could make it after a "long tunnel" 
of internal refactoring etc

The work done on the plugin side was also unexpected and not planned. It 
was just a "need" from our internal feedbacks.


> Even if the background and the advantages are not visible at first 
> glance (is there any help for this?), it certainly does no harm and 
> does not cause any extra work.
>
Maybe indeed for some checks, it's not obvious, but as you said, "it 
does not harm" to make it.

For now, we have "blocking" rules only if the issue is a "less than 1 
minute to fix", we do not block suddenly our users in their workflow.

But some checks, tagged "Important" (so not "blocking" the CFG file 
generation), are sometimes leading to poor performance of the project. 
Because it's not "quick" to fix, we decided to not block users.

I'm thinking about the "Invalid field for QGIS server", this one is an 
important check to fix, but it takes more than a minute...
We are still not sure how we will enforce this rule in the future... If 
you have ideas ? :)


These checks are coming from our internal feedbacks on our Lizmap Cloud 
hosting solution. We are monitoring a lot of customers having various 
projects (various layers, use case, different situations etc.). So these 
checks in the plugin are bottlenecks we could identify on projects we 
are hosting.

Some bottlenecks are very "project specific" sometimes, or too long to 
code for now :) So it won't land in the plugin for now.

Feel free to provide some ideas if needed, in the Lizmap plugin repository.

> But a question about the warning in the backend if the number of 
> layers is too high:
>
> Is the absolute number of layers in the project a problem or only the 
> number of active layers that also need to be rendered?
>
> In my experience, it is only the active layers.
>

Hum, for now, there isn't any check about the number of layer in the 
plugin, right ?

The performance of a project about the number of layer is very project 
specific.

Some projects with a dozen of layers can work with difficulties (because 
covering a whole country, with a lot of features, with very precise 
geometry at high-scale), and some projects with a lot of layers can work 
nicely.

On our hosting infrastructure, we are monitoring projects having more 
than 100 layers (with another threshold at 200 layers as well).


When doing a GetMap request, QGIS server loads the whole project by 
default (like all QGIS print layouts, with all logos/pictures included 
in these layouts, all layers and relations between layers...).

That's why some QGIS settings can be tuned to skip some parts when 
loading a project (skip layouts, force readonly on layers...)

Back to your question, so I guess not only "active" layers, but also 
others layers.

Of course, the number of "rendered" layers in a GetMap request is 
important (like complexity in the symbology, the precision of the 
geometry rendered etc).


I hope I understood your question ;-)


Regards,




> Regards
>
> Günter Wagner
>
> *WAGNER-*IT**
>
> Ingenieurbüro für Geoinformatik*
> *Carl-Orff-Weg 7
> 79312 Emmendingen
> Tel.:  07641/9621668
> Fax:  07641/915599
> www.wagner-it.de <http://www.wagner-it.de/>
>
>
> _______________________________________________
> Lizmap mailing list
> Lizmap at lists.osgeo.org
> https://lists.osgeo.org/mailman/listinfo/lizmap
-- 

Etienne Trimaille
Géomaticien
www.3liz.com <http://www.3liz.com>

*Tel.* 06 12 93 11 39
*Bureau*
31, rue de l'Argenterie
34000 Montpellier
*Siège social*
73, allée Kleber
Boulevard de Strasbourg
34000 Montpellier

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