Bug report #20298
Invalid layer not freed when added to the registry
|Affected QGIS version:||2.18.25||Regression?:||No|
|Operating System:||Linux and Windows||Easy fix?:||No|
|Pull Request or Patch supplied:||No||Resolution:||end of life|
|Crashes QGIS or corrupts data:||No||Copied to github as #:||28119|
This simple code
l = QgsVectorLayer("mydb.sqlite|layername=invalid_layer", "l", "ogr") QgsMapLayerRegistry.instance().addMapLayer(l)
where l points to a valid SQLite file, but an invalid table name will result in l being not valid (l.isValid() == false).
Adding this layer to the registry will keep the connection to the SQLite opened forever. Which may lead to concurrency problems (especially under Windows).
The problem seems similar with the spatialite provider.
I can't find yet where it comes from (sip bindings ? the connection pool registry ? )
QGIS 3 not affected
#1 Updated by Alessandro Pasotti almost 3 years ago
Hi Hugo, maybe totally unrelated, but just a quick note to make sure you are aware of the ongoing work on QGIS 3 bad layer handling: the basic concept is that a layer can become invalid at any time and the layer store can contain both valid and invalid layers.
#2 Updated by Hugo Mercier almost 3 years ago
Hi Alessandro, thanks for the information about the new behaviour in QGIS 3. But if I'm correct, this is unrelated to the problem here :)
And in order to complete the report, I forgot to mention the problem is that the layer is not freed even after calling QgsMapLayerRegistry.instance().removeAllMapLayers() and after making sure all local variables are destroyed.
It can be tested by running (under linux) something like 'lsof -c "qgis" | grep "t.sqlite"' and see that the opened sqlite file is still opened.
Maybe it is due to the "/Transfer/" keyword on qgsmaplayeregistry.sip ? in case the passed layer is actually not added to the registry, Python's ref count still gets a +1 and never gets a -1 ?
#6 Updated by Giovanni Manghi over 2 years ago
- Resolution set to end of life
- Status changed from Feedback to Closed
End of life notice: QGIS 2.18 LTR
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