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I am using QGIS 3.24.2 Tisler. Machine is an i9-7900 @3.30 Ghz 64 GB RAM using Windows 11 64bit. Disk is SSD and Gfx card is a RTX2060he

When doing a raster merge (Raster - misc - merge) of multiple asc files QGIS is only using a single logical core. I can see that core being maxed out with all the other 19 sitting there idle. Disk I/O is minimal and GFX card utilisation is again minimal. Memory utilisation is about 15%

In options I have Render layers in parallel using many CPU cores enabled.

Is the merge a single core operation or should it be using multiple cores? If the latter any idea whay it isn't doing so?

Mapperz
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Richard Cutts
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  • Raster rendering has nothing to do with GDAL libraries. https://docs.qgis.org/testing/en/docs/user_manual/processing_algs/gdal/rastermiscellaneous.html#merge – Comrade Che May 05 '22 at 11:30
  • So does that mean that waht i am attempting to do is a single core activity or is it possible to have it use multiple cores? If it is how? – Richard Cutts May 09 '22 at 10:27
  • This means that you need to find out if the GDAL library supports multiple processors for data processing. – Comrade Che May 09 '22 at 11:24
  • I am not being deliberately obtuse here but i have no idea what you are talking about. the link you provided is no help at all without some context. does the operation i am doing have multi core support, or is it a singe core operation? if it depends on a setting or a particular configuiration what is that setting? – richard cutts May 09 '22 at 21:30

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One of the GDAL tools (gdalwarp) supports multiprocessing: Does GDAL support parallel processing?.

To use it as described here, you must use the -multi keyword.

It seems merge tool does not support multiprocessing because there is no such option in the merge tool description.

Comrade Che
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