XML parsing slows down WFS and GML loading

[qgib]

Author Name: Paolo Cavallini (@pcav)
Original Redmine Issue: 2297

Redmine category:data_provider
Assignee: nobody -

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WFS loading is very slow: I always thought that was due to bandwidth, but now it seems more likely that XML parsing is the culprit (thanks Furieri for noticing!). The same can be see in GML loading from local file. The effect seems particularly heavy on Windows.

[qgib]

Author Name: Marco Hugentobler (@mhugent)

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Is there a test server instance / test file?
The WFS provider uses a different approach than the GML reader of OGR. So probably they are slow for different reasons.
And yes, reading XML is more demanding performance wise than reading the same information in a binary format.

[qgib]

Author Name: Paolo Cavallini (@pcav)

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This should be a good and fast server, rather slow to download:

http://webgis.regione.sardegna.it/geoserver/wfs?

[qgib]

Author Name: Paolo Cavallini (@pcav)

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While loading, the bottleneck seems CPU, that goes up (98-99%)

[qgib]

Author Name: Marco Hugentobler (@mhugent)

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I tested it with the layer ras:IDT_MN11V_DATI_AGGR_PROV. (22MB) with wget and the WFS plugin. I didn't measure the time exactly, but it seemed comparable to me, appr. 60 - 70 seconds.

The reason the CPU works while loading is that the WFS provider does asynchronous request and starts parsing before the whole document has arrived.

[qgib]

Author Name: Paolo Cavallini (@pcav)

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So better close it - still unsure about GML though, but this will require more testing, especially on Windows.

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