Universal Windows App - high CPU usage



  • Hello!

    "Empty" Qt 5.7 Widgets Application overloads one CPU core on my Windows 10. Just created new project and pressed start button. Debugger shows main thread lambda_invoker_stdcall as start point and Qt5Cored.dll as active code.

    Any ideas how it could be avoided or foxed&


  • Moderators

    @aktk

    Which start button do you mean? The debugger one?

    Did you do already a rerun qmake and rebuild?



  • Under start button I mean Run (Ctrl+R) button

    Project is clean, just created for test Qt Widgets Application - no changes befor run, just created new project and run it. No interactions with app.

    I've tested on two machines - real one and VM. On both of them one CPU core was fully used with single app thread. Looks like messages processing loop iterates without any waits or smth like this.


  • Moderators

    @aktk

    Sounds really strange. For which compiler did you do the installation?



  • @koahnig
    MS VC 2015
    I've used qt-opensource-windows-x86-winrt-msvc2015-5.7.0.exe


  • Moderators

    @aktk

    I have used Qt creator and generated just the templated app compiled and started. It has no problem.

    However, I am on windows 10 and I am using MinGW compiled libs Qt 5.7.0.

    When you are using vsaddin for VS2015, this might be already different. I doubt that there is a general issue for VS2015. You could Qt creator together with VS2015 compiler for a check.

    Are you using vsaddin?

    You can check on JIRA for a possible known bug for vsaddin.

    I had used vs2005 with vsaddin quite a while ago. I was not really convinced of this. However, there have been updates especially for Qt5. In general there seem to be less users using vsaddin since it requires a full version of VS and cannot be used with the free express version.



  • Nope - I'm not using vsaddin



  • @koahnig
    Jira does not contain any similar issue - wrote email directly to WinRT port owner, hope it could help )


  • Moderators

    @aktk

    You wrote an email or filed a bug report?
    The proper way would be writing a bug report. Not sure if you can write emails directly there.

    Typically it is also good to have a link here to bug reports in case someone stuumbles into the same problem. Also people can upvote on JIRA to create more urgency with their votes.



  • @koahnig

    Thank you for advices!

    Created a ticket - https://bugreports.qt.io/browse/QTBUG-57579


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