High memory usage with Snap geometries to layer and "exception:unknown" message

[qgib]

Author Name: Antoine Lafranchis (@alafr)
Original Redmine Issue: 19436
Affected QGIS version: 3.7(master)
Redmine category:digitising

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In some circumstances, the computer freezes with 99.9% memory usage (then task manager stops responding...) when using the algorithm 'Snap geometries to layer'.
It apparently happens only when snapping a line layer to a point reference layer, with a small tolerance (0.00001 or lower).
It happend initially on a huge shapefile with geometry errors, but then I could reproduce it with tempopary layers: a line layer with a single line and a point layer with 3 points: the 1st point was precisely on a vertex, the 2nd point close to a second vertex (within the tolerance radius) and the 3rd point quite far from the line.

Because I had to "brutally" shut down and restart the computer, I don't have any test file to attach and no crash log. The only details that were left were the processing history: ```processing.run("qgis:snapgeometries", {'INPUT':'Point?crs=EPSG:4326&uid={50146ea0-3a7a-4515-8241-e842f2ef1717}','REFERENCE_LAYER':'LineString?crs=EPSG:4326&uid={c6586332-d416-495e-868d-e34430dab439}','TOLERANCE':1e-5,'BEHAVIOR':0,'OUTPUT':'memory:'})

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- [test_project.qgz](https://issues.qgis.org/attachments/download/14412/test_project.qgz) (Antoine Lafranchis)
- [test_memory_usage.png](https://issues.qgis.org/attachments/download/14413/test_memory_usage.png) (Antoine Lafranchis)
- [QGIS.zip](https://issues.qgis.org/attachments/download/14425/QGIS.zip) (Antoine Lafranchis)
- [test_snap_config.png](https://issues.qgis.org/attachments/download/14426/test_snap_config.png) (Antoine Lafranchis)
- [qgis_version.png](https://issues.qgis.org/attachments/download/14427/qgis_version.png) (Antoine Lafranchis)
- [qgis_snap_exception.png](https://issues.qgis.org/attachments/download/14428/qgis_snap_exception.png) (Antoine Lafranchis)

[qgib]

Author Name: Nyall Dawson (@nyalldawson)

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Duplicate of #26385

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

[qgib]

Author Name: Antoine Lafranchis (@alafr)

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I still experience abnormally high memory usage and Qgis freezing when snapping points to lines with small tolerance.
This time i ended qgis-dev from the task manager without waiting for the probable crash so that i could send this update.
Memory usage was at 2.5 GB and continuously increasing. The 2 shapefiles contain only 6 features in total.
It's apparently not a duplicate of #26385 which is fixed.

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• 14412 was configured as test_project.qgz
• 14425 was configured as QGIS.zip
• 14426 was configured as test_snap_config.png
• 14413 was configured as test_memory_usage.png
• status_id was changed from Closed to Reopened

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• test_project.qgz (Antoine Lafranchis)
• QGIS.zip (Antoine Lafranchis) - Shapefiles
• test_snap_config.png (Antoine Lafranchis)
• test_memory_usage.png (Antoine Lafranchis)

[qgib]

Author Name: Giovanni Manghi (@gioman)

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Antoine Lafranchis wrote:

I still experience abnormally high memory usage and Qgis freezing when snapping points to lines with small tolerance.
This time i ended qgis-dev from the task manager without waiting for the probable crash so that i could send this update.
Memory usage was at 2.5 GB and continuously increasing. The 2 shapefiles contain only 6 features in total.
It's apparently not a duplicate of #26385 which is fixed.

sure have you tested a recent build?

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• resolution was changed from duplicate to
• status_id was changed from Reopened to Feedback

[qgib]

Author Name: Antoine Lafranchis (@alafr)

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I use build 4d5dad8.
I tried again to snap the same layers and waited. It didn't actually crash, memory usage peaked at 2.6 GB then dropped suddenly and displayed an "exception:unknown" message.

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• 14428 was configured as qgis_snap_exception.png
• 14427 was configured as qgis_version.png

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• qgis_snap_exception.png (Antoine Lafranchis) - exception message
• qgis_version.png (Antoine Lafranchis) - qgis version

[qgib]

Author Name: Giovanni Manghi (@gioman)

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• category_id was changed from Processing/Core to Digitising
• status_id was changed from Feedback to Open
• priority_id was changed from High to Normal
• version was changed from 3.2 to 3.7(master)
• crashes_corrupts_data was changed from 1 to 0
• subject was changed from Windows crash with Snap geometries to layer to High memory usage with Snap geometries to layer and "exception:unknown" message

[gioman]

test_snap_config.png (Antoine Lafranchis)

On the latest master, using such (unnecessary?) small tolerance, it (still) leaks memory eating up all of it and causing a system freeze.

[gacarrillor]

This was solved by #44766

Please reopen if necessary.