[dolphin] [Bug 429725] New: Parallelize thumbnail generation on multicore systems

[Florian Dittmer]

https://bugs.kde.org/show_bug.cgi?id=429725

            Bug ID: 429725
           Summary: Parallelize thumbnail generation on multicore systems
           Product: dolphin
           Version: 20.08.3
          Platform: Other
                OS: Linux
            Status: REPORTED
          Severity: normal
          Priority: NOR
         Component: view-engine: icons mode
          Assignee: dolphin-bugs-null at kde.org
          Reporter: kde-bugs at pyoworks.com
                CC: kfm-devel at kde.org
  Target Milestone: ---

SUMMARY

I have folders with lots of images. My system is a modern 8core/16thread Ryzen
with NVMe storage and 32GB of RAM. When opening a folder in "thumbail view" for
the first time, Dolphin will start thumbnail generation. Looking at the "top"
output, I can only see one thumbnail.so process while most of the CPU cores are
idle.

Is it possible to parallelize the thumbnail generation to make it faster? E.g.
when opening a folder with 100 images, why not divide them and start X threads
of the thumbnail generator in parallel? Number of threads could be calculated
based on number of cores/threads and/or made configurable to fit user needs.


STEPS TO REPRODUCE
1. Open folder with logs of images in Dolphin in icon/thumbnail mode
2. Look at top/ps -> only one thumbnail.so process processing sequentially the
directory, other cpu cores idle.
3. 

OBSERVED RESULT


EXPECTED RESULT


SOFTWARE/OS VERSIONS
Operating System: Gentoo Linux
KDE Plasma Version: 5.19.5
KDE Frameworks Version: 5.74.0
Qt Version: 5.15.1
Kernel Version: 5.9.11
OS Type: 64-bit
Processors: 16 × AMD Ryzen 7 3700X 8-Core Processor
Memory: 31.4 GiB of RAM
Graphics Processor: AMD Radeon RX 5700 XT

ADDITIONAL INFORMATION

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