[Qgis-developer] [Server] performance questions

[Alessandro Pasotti]

2016-02-23 15:20 GMT+01:00 Régis Haubourg <
regis.haubourg at eau-adour-garonne.fr>:

> Hi all,
> we are working on using qgis server here and we face some performance
> issues
> on big data sets. Cache is not an option for those layers that will be
> edited by users. Currently performances are not acceptable for production
> uses.  Here is a couple of questions that I could not answer by myself on
> the net:
>
> 1- Clarifying multithread on server side vs multithread on desktop:
>
> We use qgis 2.12 server from qgis repository for debian on a 4 core Xeon
> (2.1Ghz) + 16Go RAM.
>
> We configured apache2 with MPM worker and we have a pool of 10
> qgis_mapserv.fcgi waiting for client request.
> The behaviour here is that one client will only consume one fcgid process,
> when desktop can use several processes to make some parallel rendering of
> project layers.
> When having QGIS desktop  using only one thread, I have similar rendering
> time. The difference is purely proportionnal to CPU speed difference.
> Did we miss something in configuration process or is that the intended
> behavior? I did try to use QGIS_OPTION_PATH on a QGIS2.ini but I really
> can't be sure it is really being used.
> Do QGIS packages miss the multithread option on compile cmake options?
> If this is expected, does the web architecture would allow to have fcgid do
> parallel rendering like desktop? Would that be a big work (I could partly
> fund that)?
>
>
> 2- Overhead on first request with postgres complex view compared to
> shapefiles
>
> We have almost only postgis views being used as QGIS layers. Qgis server
> builds get capabilities and requests views to get extent and primary keys.
> There is a severe overhead for the first wms request by a client session.
> When generating the image takes about 7s, the first request can take from
> 24
> to 30s. Desktop multihreaded will get the image in about 3s (same postgres
> server, same network).
> That overhead starts to become annoying on desktop side too, but it's only
> qgs loading time, once in a work session. Does someone have any idea that
> one day postgis could collect such metadata on views so that QGIS do not
> have to scan all rows when data are in views? Direct access to tables, or
> same project with shp datasources do not show that overhead on server nor
> in
> desktop.
>


Hi,

For your point 2, is this bug related to your issue
http://hub.qgis.org/issues/13232 ?


-- 
Alessandro Pasotti
w3:   www.itopen.it
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.osgeo.org/pipermail/qgis-developer/attachments/20160223/f50ccd0c/attachment.html>