Switches on the sip "-g" switch, which forces sip to release the
Python Global Interpreter Lock before calling a qgis c++ method,
and reacquire it after.
While this flag is not a default sip flag, it is used when building
the PyQt API, so can't forsee any issues from enabling it.
The benefit however is extreme for PyQGIS based scripts which
rely on threads, potentially resulting in massive performance
boosts.
Without this switch, calling an expensive c++ method (say,
building a QgsSpatialIndex using a QgsFeatureIterator) would lock
the Python GIL for the duration of the c++ call... which could
potentially take minutes or more. With the switch, the lock
is released before all calls, so other Python threads are free
to merrily grab the lock and do other processing while the
original thread chugs away in c++ land.
Benchtests of worst-case scenarios (single thread calling
thousands of very inexpensive PyQGIS methods (simple getters))
regressed from mean of 154 seconds to 158 with this flag. But
that's worst case (and as Intel have recently demonstrated...
we can't take yesterday's computing speed as the benchmark
for todays ;). Given that best case scenarious (multi-threaded
operations calling slow c++ methods) will benefit so greatly
from this change, I think it's an acceptable trade off.
*This is a step toward potentially re-enabling background
execution of python based Processing algorithms, and also
should greatly improve QGIS responsiveness when using
python based renderers/symbols.
I wanted to add the test for gpkg subsetstring even if
it was not bugged, while testing that, I hit an assert
in Qt core that pointed me to double unlocked locks.
options should be available for certain model outputs and script
algorithm outputs
We do this by swapping the test for non-file based output support
from checking only the algorithm's provider to instead checking
on a parameter-by-parameter basis.
This is done in order to support models. For models, depending
on what child algorithm a model output is based off, an individual
model may or may not have support for non-file based outputs. E.g
a model may generate outputs from a native qgis alg (supporting
these outputs) AND an output from a GDAL alg (with no support
for these outputs). In this case we need to enable or disable
the ui controls for non-file based outputs on an individual
output basis.
For scripts (for now) we blindly just say all outputs support
non-file based formats. This is going to be the case most of
the time, since scripts will usually be written using PyQGIS
API. For the exceptions (e.g. scripts which call other algs
like GDAL algs) we probably should add some way for the script
to indicate whether an individual output supports this, but
for now we just say they all do.
Fixes#17949
Fixes a typo in QgsCoordinateReferenceSystem::syncDb() that improperly set "Imported from GDAL" as name for all geographical coordinate systems imported from GDAL/PROJ definitions during postintall CRS database synch.
Fixes#17941
