100% cpu load when debugging Qt application at a certain level of memory.



  • Hay,

    We experience a strange problem at Wince7 and debugging Qt applications with visual studio 2008, the version of Qt used is the 4.8.4.
    When debugging our application the cpu raises towards 100% when a certain level of ram memory left on the device is met.

    the following findings we have:
    qdeclarative application and own libs shows the problem at 27Mb of ram left.
    qdeclarative aplication without own libs show the problem at 12Mb of ram left.
    qtApplication with only qtCore lib still shows the problem at 3 Mb of ram left.

    The stranges thing on this is the correlation of used libs (size of program) and the point of crashing with the amount of memory left.

    As a setup we have a simple qt application with the following content. We launch that application trough the debugger and everything runs fine. In other test we put a breakpoint at app.exec() and the behaviour willl also be present when we play with the memory. So there must be someting in the QApplication instantatied that causes the problem.
    @
    int main(int argc, char *argv[])
    {
    QApplication app(argc,argv);
    app.exec();
    }
    @

    In parallel we have a memory consumer next to it, it is a native c++ application, to make it ease we put a breakpoint at the sleep to control the memory consumption. So we launch that application throug the debugger or on the platform itself. When a certain level of memory is left we see an increase of 100% cpu load at our wince7 devices. We tried it already on 2 different manufactured platforms, so there must be a correlation between wince and the initialized QApplication.
    @
    #include "stdafx.h"
    #include <winbase.h>

    int _tmain(int argc, _TCHAR* argv[])
    {
    malloc(20000000);
    int i = 0;
    while(1)
    {
    malloc(1000000);
    Sleep(1000);
    }
    return 0;
    }
    @

    Does anyone sees the same behaviour on a wince device as well or does anyone has an idea of a library who can cause such a behavior?


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