Line layer labeling eats up all memory

[qgib]

Author Name: Sandro Santilli (@strk)
Original Redmine Issue: 4083
Affected QGIS version: master
Redmine category:labelling

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At high zoom levels, layer with new layer labeling activated consume lots of memory. So much to eventually render the machine unusable.

Il'll attach a shapefile with the data I'm testing this with.

To reproduce:

• Open the shapefile as a layer
• Zoom in as much as possible on the left-most node
• Enable labeling

This is happening as of 3ac604f (1.7.0+)

I haven't tried with POINT or POLYGON layers.

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• un_dump.shp (Sandro Santilli)
• un_dump.dbf (Sandro Santilli)
• un_dump.shx (Sandro Santilli)
• bug4083.qgs (Sandro Santilli)
• bug4083-2.qgs (Sandro Santilli)

[qgib]

Author Name: Martin Dobias (@wonder-sk)

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I am unable to reproduce the issue here. Could you please try to provide a sample project file with configured labeling and map canvas zoomed in?

[qgib]

Author Name: Sandro Santilli (@strk)

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It's not that easy, as if I zoom in enough to reproduce the problem I end up being unable to get control of the machine, so have to kill qgis which then fails saving the project...

[qgib]

Author Name: Sandro Santilli (@strk)

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The attache project is at a zoom level good enough to see memory growing. Zoom further to kill the machine...

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• 3340 was configured as bug4083.qgs

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• bug4083.qgs (Sandro Santilli)

[qgib]

Author Name: Sandro Santilli (@strk)

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Second version of project file manually tweaked to make the problem more visible.

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• 3341 was configured as bug4083-2.qgs

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• bug4083-2.qgs (Sandro Santilli)

[qgib]

Author Name: Martin Dobias (@wonder-sk)

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Thanks. Now I am able to reproduce the problem.

The labeling library tries to create a huge number of label candidates. The number of candidates is approximately (line length) / (label width) and that is a lot when zoomed in.

I think this should be solved by clipping lines that are not entirely in the view. This would also solve the problem of missing labels when zoomed in (= labels outside current extent).

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• assigned_to_id was configured as Martin Dobias

[qgib]

Author Name: Martin Dobias (@wonder-sk)

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I have added clipping of input geometries in 17e864b which fixed that.

It's in master branch. I will rather not commit that to 1.7 branch since the clipping might have further side effects I am not aware of.

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• resolution was changed from to fixed
• status_id was changed from Open to Closed

[qgib]

Author Name: Sandro Santilli (@strk)

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I'm still using 1.7 and this remains the most hit issue I have. Your commit cherry-picks cleanly in 1.7, I'm giving it a try there. The worst that can happen with clipping is an exception, but since qgis uses the C-API it'll be a NULL return which you're handling by skipping labeling for that feature (if I read the code correctly).

I'm also guessing the patch is not in 1.8 as I don't see any other commit referenced in "Associated revisions". It'll be important to backport at least there IMHO.

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• pull_request_patch_supplied was configured as 0
• crashes_corrupts_data was configured as 0
• version was configured as master
• status_id was changed from Closed to Reopened

[qgib]

Author Name: Sandro Santilli (@strk)

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Alright, I did hit one of those drawbacks pretty easily :)
That was: ST_Intersection returns a geometry of a different type, with the consequence of the code taking who knows what path, a popup window showing complaining about unknown geometry type and the UI entering the infinite rounding circle :) Oops

[qgib]

Author Name: Giovanni Manghi (@gioman)

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can you test with master? thanks.

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• status_id was changed from Reopened to Feedback

[qgib]

Author Name: Alister Hood (@AlisterH)

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• category_id was changed from Symbology to Labelling

[qgib]

Author Name: Paolo Cavallini (@pcav)

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• fixed_version_id was configured as Version 2.0.0

[qgib]

Author Name: Giovanni Manghi (@gioman)

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Sandro Santilli wrote:

Alright, I did hit one of those drawbacks pretty easily :)
That was: ST_Intersection returns a geometry of a different type, with the consequence of the code taking who knows what path, a popup window showing complaining about unknown geometry type and the UI entering the infinite rounding circle :) Oops

it seems to work fine on the latest master, please leave feedback.

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• assigned_to_id removed Martin Dobias

[qgib]

Author Name: Giovanni Manghi (@gioman)

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Closing for lack of feedback. I assume that this was fixed. Please reopen if necessary.

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• status_id was changed from Feedback to Closed