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Multithreading and QML

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  • V Offline
    V Offline
    vidar
    wrote on last edited by
    #1

    Hi,

    I started a qml-based Application. It does some expensive calculation inside a separate QThread and emits a signal to QML in order to update a ProgressBar.

    However, setting the new ProgressBar value results in a segmentation fault and the debug info:
    "Invalid parameter passed to C runtime function.
    ASSERT: "engine->jsStackTop >= mark" in file ....\include\QtQml\5.2.0\QtQml/private/../../../../../src/qml/jsruntime/qv4scopedvalue_p.h, line 74"

    I am pretty sure there is no mistake in my code. ;) So it just seems as if QML is not ready for this kind of multi-threading. Do you have any ideas or experience with multithreading and QML?

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    • sierdzioS Offline
      sierdzioS Offline
      sierdzio
      Moderators
      wrote on last edited by
      #2

      Make sure you emit that signal using a Qt::QueuedConnection.

      (Z(:^

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      • V Offline
        V Offline
        Vincent007
        wrote on last edited by
        #3

        check whether you are using QThread correctly.
        Are you sure that signal is emitted inside another thread instead of main thread?

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        • M Offline
          M Offline
          MatesCZ
          wrote on last edited by
          #4

          Vidar: How did you solved it? I came across the same problem...

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