Hi they are triggered by QgsMapCanvas (in the gui library), so I would be very surprised if they were triggered on the server.
Matthias On 11/16/2017 02:29 PM, kimaidou wrote: > Hi, > > I was wondering if these preview jobs are enabled in QGIS Server > context, when requesting a GetMap from any client. I am pretty sure > the context of the preview jobs execution is related to Desktop, but I > would like to be sure. > Any hint on this ? > > Regards, > Michaël > > 2017-11-16 11:15 GMT+01:00 Matthias Kuhn <[email protected] > <mailto:[email protected]>>: > > Hi Patrick, > > Would be interesting to do this test with previews enabled and > disabled. Then we'll see if it's actually the previews or some > other mechanism that is causing this. > > IIRC only a composite image is saved in the preview jobs and not > each layer separately, but that's just what I remember and not > evidence based. > > You can enable them in the python console with > > iface.mapCanvas().setPreviewJobsEnabled(True) > > and disable with > > iface.mapCanvas().setPreviewJobsEnabled(False) > > Thanks for a feedback > > Matthias > > > On 11/16/2017 08:42 AM, Patrick Dunford wrote: >> >> In my current project using Qgis 2.99, turning off the rasters >> uses 16 GB, turning them on uses 52 GB >> >> I do not believe it is independent from the number of layers that >> are being displayed. >> >> Previous versions of the software did not cache every single >> raster (the number of rasters actually being displayed on the >> canvas at any one time is a small fraction of the total number in >> the project) >> >> On 16/11/17 20:11, Matthias Kuhn wrote: >>> >>> Hi Patrick, >>> >>> This uses some memory (~ canvas width pixels * canvas height >>> pixels * 8 preview images * 32 bit RGBA), so let's assume 50 MB >>> to 100 MB. >>> >>> This consumption is independent from the number or type of layers. >>> >>> Matthias >>> >>> >>> On 11/16/2017 08:02 AM, Patrick Dunford wrote: >>>> >>>> So to put it another way this is the reason why Qgis wants to >>>> use a huge amount of memory (40 GB) when I have a lot of raster >>>> images loaded in the background. >>>> >>>> >>>> On 16/11/17 18:56, Tim Sutton wrote: >>>>> Hi >>>>> >>>>>> On 16 Nov 2017, at 04:35, Patrick Dunford >>>>>> <[email protected] <mailto:[email protected]>> wrote: >>>>>> >>>>>> What is this "preview job" function? >>>>>> >>>>>> >>>>> >>>>> Its application logic to prefetch / pre-render offscreen >>>>> content in anticipation of user panning the map. >>>>> >>>>> Regards >>>>> >>>>> Tim >>>>>> >>>>>> _______________________________________________ >>>>>> QGIS-Developer mailing list >>>>>> [email protected] >>>>>> <mailto:[email protected]> >>>>>> List info: >>>>>> https://lists.osgeo.org/mailman/listinfo/qgis-developer >>>>>> <https://lists.osgeo.org/mailman/listinfo/qgis-developer> >>>>>> Unsubscribe: >>>>>> https://lists.osgeo.org/mailman/listinfo/qgis-developer >>>>>> <https://lists.osgeo.org/mailman/listinfo/qgis-developer> >>>>> >>>>> — >>>>> >>>>> >>>>> >>>>> >>>>> >>>>> >>>>> *Tim Sutton* >>>>> >>>>> *Co-founder:* Kartoza >>>>> *Project chair:* QGIS.org <http://QGIS.org> >>>>> >>>>> Visit http://kartoza.com <http://kartoza.com/> to find out >>>>> about open source: >>>>> >>>>> Desktop GIS programming services >>>>> Geospatial web development >>>>> GIS Training >>>>> Consulting Services >>>>> >>>>> *Skype*: timlinux >>>>> *IRC:* timlinux on #qgis at freenode.net <http://freenode.net> >>>>> >>>> >>>> >>>> >>>> _______________________________________________ >>>> QGIS-Developer mailing list >>>> [email protected] >>>> <mailto:[email protected]> >>>> List info: https://lists.osgeo.org/mailman/listinfo/qgis-developer >>>> <https://lists.osgeo.org/mailman/listinfo/qgis-developer> >>>> Unsubscribe: https://lists.osgeo.org/mailman/listinfo/qgis-developer >>>> <https://lists.osgeo.org/mailman/listinfo/qgis-developer> >>> >>> >>> >>> _______________________________________________ >>> QGIS-Developer mailing list >>> [email protected] >>> <mailto:[email protected]> >>> List info: https://lists.osgeo.org/mailman/listinfo/qgis-developer >>> <https://lists.osgeo.org/mailman/listinfo/qgis-developer> >>> Unsubscribe: https://lists.osgeo.org/mailman/listinfo/qgis-developer >>> <https://lists.osgeo.org/mailman/listinfo/qgis-developer> >> >> >> >> _______________________________________________ >> QGIS-Developer mailing list >> [email protected] >> <mailto:[email protected]> >> List info: https://lists.osgeo.org/mailman/listinfo/qgis-developer >> <https://lists.osgeo.org/mailman/listinfo/qgis-developer> >> Unsubscribe: https://lists.osgeo.org/mailman/listinfo/qgis-developer >> <https://lists.osgeo.org/mailman/listinfo/qgis-developer> > > > _______________________________________________ > QGIS-Developer mailing list > [email protected] <mailto:[email protected]> > List info: https://lists.osgeo.org/mailman/listinfo/qgis-developer > <https://lists.osgeo.org/mailman/listinfo/qgis-developer> > Unsubscribe: > https://lists.osgeo.org/mailman/listinfo/qgis-developer > <https://lists.osgeo.org/mailman/listinfo/qgis-developer> > >
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