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macOS Mojave and Threaded render

  • I just figured out how to add threaded rendering to my app only to find it no longer works in Mojave. BIG PROBLEM (I've read bug reports and multiple examples saying to use QSG_RENDER_LOOP=basic).

    My app looks terribly jittery using the basic render thread, and beautiful using QSG_RENDER_LOOP= threaded.

    This is kind of urgent for me : Is there a way to use Threaded, GPU-enabled rendering in macOS Mojave?

    I'm using 5.12.0 at the moment.


  • *** Workaround *** Please read:

    • Downloaded XCode 9.4.1 from the Apple Dev Site (
    • Downloaded and installed Command Line Tools as well (same link)
    • Ran

    sudo xcode-select --switch /Applications/Xcode\

    • Restarted, opened XCode (for setup), opened Qt, created new Kit setup using clang++ from XCode 9, rebuilt app and it works.

    So I have things working well, but I'd like to see this issue addressed in an update - without Threaded Rendering any movement of large bitmaps on the screen looks terrible.

    Hope this helps someone else.

  • Lifetime Qt Champion


    You should check whether the issue still arises with the latest Qt 5.12 release and if so with the latest beta of Qt 5.13.

    Then you should check the bug report system to see if there's already a report about that. This is a user forum and thus not there right place to get such issue addressed.

  • Hi @SGaist , I did try the updated version, and I spent hours digging through the bug reports (which is how I realized the threaded rendering was what was causing the apps to crash), so it's a known issue already, but the temporary solution is not easy to find, so I wanted to share for others who need help in an emergency.

  • Lifetime Qt Champion

    Nice of you, thank you !

    Would you mind posting the bug report link ? That will also be helpful for people finding this thread.

  • This is the bug report:

    From what I've read, it is recommended now to just use Basic render mode (if you need to use XCode 10+, which really makes Qt for visually complex macOS apps perform terribly.

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