[Qgis-developer] [QGIS Server] How to share QgsPostgresSharedData between multiple QGIS instances

[Alessandro Pasotti]

On Thu, Dec 22, 2016 at 5:20 PM, Matthias Kuhn <matthias at opengis.ch> wrote:

> On 12/22/2016 05:06 PM, Alessandro Pasotti wrote:
> > On Thu, Dec 22, 2016 at 4:10 PM, Matthias Kuhn <matthias at opengis.ch
> > <mailto:matthias at opengis.ch>> wrote:
> >
> >     Hi Alessandro
> >
> >     >
> >     > In Lyon we also talked about how to share caches between different
> >     > server processes, do you think that the shared memory segment
> would be
> >     > appropriate in that case?
> >
> >     What are the caches used for?
> >
> >
> > mainly per-project capabilities.
> >
> > With QGIS 3 refactoring the QgsProject class will probably hold all the
> > information we need instead of parsing the project XML like we are doing
> > now, I think that we'll need to cache the QgsProject instance itself if
> > we want scalability by spawning multiple server processes without the
> > need to re-parse the project file, this in case we need to serve
> > multiple projects of course.
>
> Is there some profiling information available about what's the slow part
> (parsing, loading of layers, loading of print composers...)?
>


I think Patrick was working on profiling.
BTW, the thing are probably going to change significantly after the
refactoring that will use the new QgsProject.



>
> Saving a whole project including layers etc. in a shared memory sounds
> like a challenge.
> It's possibly easier to identify which parts are slow and cache them on
> some backend.
> If this mechanism is abstract enough to work with a file based format
> like sqlite or memcached/redis, that would be awesome because QGIS
> desktop could also benefit and depolyment on a server will probably be
> easier if it does not depend on additional services.
>



-- 
Alessandro Pasotti
w3:   www.itopen.it
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