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PDF export heat up i.mx6

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i.mx6qprinterqwebkit
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  • P Offline
    P Offline
    PhTe
    wrote on last edited by
    #1

    Hi,
    i use an i.mx6 cpu with linux os for a qt5.4.1 application.
    In this application i use the following function to export some html pages to pdf files.

    bool PdfExport::exportFile(const char *path) {
        QWebPage page;
        page.mainFrame()->setHtml(exportString().c_str());
    
        // printer is a QPrinter member variable of the PdfExport class
        printer->setPageMargins(5, 5, 5, 5, QPrinter::Millimeter);
        printer->setOutputFileName(path);
        printer->setPageSize(QPrinter::A4);
        printer->setPrintRange(QPrinter::AllPages);
    
        page.mainFrame()->print(printer);
    
        return true;
    }
    

    As long as i do not call the function, my cpu has a constant temperature of 45°C (CPU load ~35%).
    But after i call it the temperature rise quickly to around 60°C, stays there and does not went down any more. Even if i wait an hour or so. CPU usage is furthermore at ~35%.
    I think the GPU will heat up the chip, but why? My function does not hang and returns in a split second.

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    • jsulmJ Offline
      jsulmJ Offline
      jsulm
      Lifetime Qt Champion
      wrote on last edited by
      #2

      Here http://forum.solid-run.com/linux-on-cubox-i-and-hummingboard-f8/temperatures--t490.html
      I found the information that 85-90 degree is normal for that CPU.
      How long do you wait before you execute exportFile()? Maybe 60 degree is normal.

      https://forum.qt.io/topic/113070/qt-code-of-conduct

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      • P Offline
        P Offline
        PhTe
        wrote on last edited by
        #3

        I have waited different times. The longest was around 1 and a half our, and the temperature was never higher than 45°C.
        Then i call the export function and the temperature rise up to 60°C in less then 20 seconds and stays there until i close my application. If my application is not running and the os is idle the temperature is around 38°C.

        So 60°C is definitely not normal.

        jsulmJ 1 Reply Last reply
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        • M Offline
          M Offline
          mvuori
          wrote on last edited by
          #4

          Perhaps your printer object has been stuck in a loop of some sort. You could delete the printer after printing and see what happens. Perhaps printer could be a local in that function and be deleted automatically when not needed anymore, but you are best in thinking of such architectural questions.

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          • P PhTe

            I have waited different times. The longest was around 1 and a half our, and the temperature was never higher than 45°C.
            Then i call the export function and the temperature rise up to 60°C in less then 20 seconds and stays there until i close my application. If my application is not running and the os is idle the temperature is around 38°C.

            So 60°C is definitely not normal.

            jsulmJ Offline
            jsulmJ Offline
            jsulm
            Lifetime Qt Champion
            wrote on last edited by
            #5

            @PhTe Can you verify that your application is really not running if you close it? Is the process terminated? Maybe it is still running in the background and consumes CPU.

            https://forum.qt.io/topic/113070/qt-code-of-conduct

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            • P Offline
              P Offline
              PhTe
              wrote on last edited by
              #6

              Hey,
              thanks for your help.
              It figured out, that the problem was not the export process. Sorry :)

              It was the message window i show when the export is complete.
              I dont know why but it caused the gpu to heat up even if it was closed.

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