[Qt-interest] QProcess::execute() results in arbitrary "segmenation faults" or "illegal instructions"

[Markus Franke]

Dear all,

I am observing a strange behaviour of the QProcess::execute() function 
resulting in segmentation faults.

I have an object (see sample code below) which installs a timer. The timer 
function is called every 100ms and executes within a loop an external 
process with the help of the QProcess::execute() function.

For a couple of minutes everything is working fine and the processes are 
being executed. But then, at some point in time my whole application 
crashes with a "Segmentation fault" or "Illegal instruction" right before 
or just after the call to QProcess::execute().

I tried to achieve the same behaviour within a simple test application but 
without success. A minimal test example seems to work completely perfect. 

However I am using several threads within my application and when I stop 
all the other threads the code below seems to work again.

Might the segmentation faults maybe have something to do with my 
multithreading application? I mean actually QProcess::execute() should be 
thread-safe. Is there any bug of QProcess within in a multithreaded 
environment known?

I am using Qt Embedded 4.5.0 on an ARM based board.

Thanks for any comments on this,

Markus Franke


---snip---
#include "Page_LanguageUpdate.h"

#include <QProcess>

#define UPDATE_TIMER_MS 100 // refresh view every UPDATE_TIMER_MS 
milliseconds

TPage_LanguageUpdate::TPage_LanguageUpdate(TPageStack *StackLayout, 
TGlobals *GlobalValues, TFileSystem* pFilesystem)
{
}

void TPage_LanguageUpdate::getLanguageUpdates(void)
{
        // allow no parallel executions
        QMutexLocker locker(&UpdateRunningMutex);

        for (int i = 0; i < 10; i++)
                QProcess::execute("ls -l");

        return;
}

void TPage_LanguageUpdate::timerEvent(QTimerEvent* event)
{
        Q_UNUSED(event)

        if(event->timerId() == RefreshTimerID)
                getLanguageUpdates();
        else QWidget::timerEvent(event);
}

void TPage_LanguageUpdate::showEvent(QShowEvent* event)
{
        Q_UNUSED(event)

        DEBUG_TRACE

        RefreshTimerID = startTimer(UPDATE_TIMER_MS);
}

---snap---


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