Hi,
From bisect-like analysis, I have found the commit that introduces the
loss of loading performance:
https://github.com/qgis/QGIS/commit/c6beb62216fcfbfe3ca64283c09117da53800a98
We need more investigation to understand exactly what is causing that
regression.
David Marteau
www.3liz.com <http://www.3liz.com>
Le 21/06/2022 à 14:45, David Marteau via QGIS-Developer a écrit :
Hi,
Here is a first analysis using QgsRuntimeProfiler outputs
The project is the same in all tests and has been saved with Qgis 3.26.
This is a first load in each case just after qgis init, so there
should be no caching involved.
Output has been filtered to `projectload` profiler group and rows with
elapsed time > 0
All builds are official builds and installed from qgis.org packages.
Tests are run in Docker container with ubuntu 21.04
Total time show a variance of +/- 25% on multiple runs.
## Qgis 3.26
### Flags
* Qgis.ProjectReadFlag.TrustLayerMetadata
* Qgis.ProjectReadFlag.DontLoad3DViews
* Qgis.ProjectReadFlag.DontLoadProjectStyles
projectload, Reading project file: 21.0 ms
projectload, Creating auxiliary storage: 65.0 ms
projectload, Reading properties: 19.0 ms
projectload, Reading map layers: 14.0 ms
-projectload, france_parts: 6.0 ms
--projectload, Load layer source: 5.0 ms
---projectload, Create ogr provider: 3.0 ms
-projectload, france_parts bordure: 4.0 ms
--projectload, Load layer source: 4.0 ms
---projectload, Create ogr provider: 2.0 ms
-projectload, france_parts tuilé en cache: 3.0 ms
--projectload, Load layer source: 3.0 ms
---projectload, Create ogr provider: 1.0 ms
projectload, Storing original layer properties: 2.0 ms
Total time: 152.0 ms
## Qgis 3.24
### Flags
* QgsProject.FlagTrustLayerMetadata
projectload, Reading project file: 5.0 ms
projectload, Reading properties: 4.0 ms
projectload, Reading map layers: 4.0 ms
-projectload, france_parts: 1.0 ms
--projectload, Load layer source: 1.0 ms
-projectload, france_parts bordure: 1.0 ms
--projectload, Load layer source: 1.0 ms
-projectload, france_parts tuilé en cache: 1.0 ms
--projectload, Load layer source: 1.0 ms
projectload, Storing original layer properties: 1.0 ms
projectload, Updating interface: 1.0 ms
Total time: 21.0 ms
Some remarks:
I Wonder why we have `Creating auxiliary storage` that takes 65.0 ms
in Qgis 3.26 and it does not appears in Qgis 3.24:
I need to figure how auxiliary layers are loaded in Qgis 3.24 (are
they loaded lazily ?).
The `Reading project file`, `Reading properties` and `Reading map
layers` sections are almost 3 to 4 times slower in Qgis 3.26.
The loading of layers ares also slower in Qgis 3.26 compared to Qgis 3.24.
Le 21/06/2022 à 12:27, David Marteau a écrit :
May be I could use QgsRuntimeProfiler output in first place ?
Le 20/06/2022 à 18:55, Even Rouault a écrit :
Use sysprof or just run under a debugger and interrupt regularly
should help you spot in which method(s) most time is spent
Le 20/06/2022 à 18:48, David Marteau via QGIS-Developer a écrit :
I used the following test:
readflags = Qgis.ProjectReadFlags() readflags |=
Qgis.ProjectReadFlag.TrustLayerMetadata|Qgis.ProjectReadFlag.DontLoad3DViews|Qgis.ProjectReadFlag.DontLoadProjectStyles
prj = QgsProject()%timeit -n 1
prj.read(f"{datapath}/france_parts3_26.qgs",readflags)
105 ms ± 18.5 ms per loop (mean ± std. dev. of 7 runs, 1 loop each)
This improve the result but we are still much higher that the
loading time of 3.24: 15ms compared to 105ms
Le 20/06/2022 à 18:38, Nyall Dawson a écrit :
On Mon, 20 June 2022, 11:42 pm David Marteau, <dmart...@3liz.com>
wrote:
Hi,
> You should set the other new read optimisation flags here --
see
https://github.com/qgis/QGIS/blob/88ebb3f2f513dbce5a775f50e51ea0117f859c65/src/core/qgis.h#L1962
These are already available also in 3.24 and we use the
`TrustLayerMetadata` in the above test. For server, the other
flags are not applicable (Getprint requests need print layouts ).
So that mean we are comparing 3.24 to 3.26 with same level of
read optimisation and that does not change the fact that, for
that very same level of read optimisation, project's loading
is incredibly slower in 3.26.
You'll need to set the new flags relating to skipping the 3d views
and project style loading in order to compare properly. Neither of
those things were occurring in 3.24, and both have an associated
cost. And neither are relevant for server.
Nyall
Le 20/06/2022 à 15:10, Nyall Dawson a écrit :
On Mon, 20 June 2022, 9:37 pm David Marteau via
QGIS-Developer, <qgis-developer@lists.osgeo.org> wrote:
Hi,
I have noticed a huge drop of performance while testing
Qgis server with Qgis 3.26, from 10x to 30x slower as usual.
Trying to reduce the problem I have found a huge increase
of time spend reading the project in 3.26 compared to 3.24.
Here some benchmark with very simple project from the
test data set. Note: the project has been updated with
qgis 3.26:
Qgis 3.24:
======
readflags = QgsProject.ReadFlags()readflags |=
QgsProject.FlagTrustLayerMetadata
prj = QgsProject()
%timeit -n 1
prj.read(f"{datapath}/france_parts.qgs",readflags)
> 15.7 ms ± 205 µs per loop (mean ± std. dev. of 7 runs, 1 loop each)
Qgis 3.26:
======
readflags = QgsProject.ReadFlags() readflags |=
QgsProject.FlagTrustLayerMetadata
You should set the other new read optimisation flags here --
see
https://github.com/qgis/QGIS/blob/88ebb3f2f513dbce5a775f50e51ea0117f859c65/src/core/qgis.h#L1962
Nyall
prj = QgsProject()
%timeit -n 1
prj.read(f"{datapath}/france_parts.qgs",readflags)
195 ms ± 44 ms per loop (mean ± std. dev. of 7 runs, 1 loop each)
There is a factor x10 between Qgis 3.24 et Qgis 3.26 for
the exact same project.
This has serious impact on requests: landing page catalog
request time increased from approximatevely 110ms to more
than 3.0s with our test data set.
David Marteau
www.3liz.com <http://www.3liz.com>
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