QtConcurrentRun calls non-qt function

sharethl

Hi,

When QtConcurrentRun calls a non-qt function (c++ oop library), it has a chance to crash.
Tested multiple times under exactly same conditions.

Is this a known problem?
Or it is simply my non-qt function has bug?

Thanks.

SGaist

Hi,

QtConcurrentRun doesn't need your function to be Qt specific. Can you share the code of that function ?

sharethl

[quote author="SGaist" date="1424711613"]Hi,

QtConcurrentRun doesn't need your function to be Qt specific. Can you share the code of that function ?[/quote]

Here is QtConcurrentRun function.
_brc is an object in non-qt library.
Usually crash(show disassembler view) after line 5.

@void Spectrometer::doScanning()
{
if(_isFunctional==false) return; // disable operation if not functional

int result = _brc->startAcquiring();

//emit dataAcquisitionFinished(); // tell manager this data has been acquired.

quint16 dataBuffer[SpectrometerData::PIXEL_NUM];
if(result == 1){
    result = _brc->getYData(dataBuffer);
}
else{
    // TODO:add error message box
    return;
}

_data_ptr.data()->updateUid(); // make new id to avoid duplication.

//for flipped Spectrometer
for(int i=0;i<SpectrometerData::PIXEL_NUM;i++){
    auto y = dataBuffer[SpectrometerData::PIXEL_NUM-i-1];
    _data_ptr.data()->updateY(i,y);
}

_isWorking=false;
qDebug() << "Scan Finished";
emit scanFinished();

}@

@bool BRC::startAcquiring(){
char cmd[]="E\r\n";
int cmdLength = strlen(cmd);
if (write(_fd, cmd, cmdLength) < cmdLength){
return false;
}
return (wait("DR",cmdLength+7, _timeout));
}@

SGaist

You are trying to write on the same file descriptor from several thread at once ?

sharethl

[quote author="SGaist" date="1424727828"]You are trying to write on the same file descriptor from several thread at once ?[/quote]

No, BRC is a class, and each BRC object has its own file descriptor.

SGaist

Can you also show your call to QtConcurrentRun ?

sharethl

Device manager contains two spectrometers,

@bool DeviceManager::scan()
{
_meter0->scan(); // scan in parallel
_meter1->scan(); // scan in parallel
return true;
}@
@bool Spectrometer::scan()
{
_progress = 0;
emit reportProgress(_progress);
// this will run parallel
QtConcurrent::run(this,&Spectrometer::doScanning);
_isWorking=true;
return true;
}@

SGaist

Then are you sure that _brc is properly allocated ? That both are no trying to access the same resources at the same time ?

sharethl

_brc is a pointer in Spectrometer class.
and I use new BRC() in Spectrometer's constructor.
Works most of time.

and during my app starts up, each _brc did communicate with their corresponding hardware successfully.

Is it possible to allocate differently with same code but different runs?

SGaist

What does the backtrace of a crash tell you ?

sharethl

you mean stack trace?

two lines of ??

[quote author="SGaist" date="1424896978"]What does the backtrace of a crash tell you ?[/quote]

SGaist

Are you running a debug build ?

sharethl

[quote author="SGaist" date="1424993803"]Are you running a debug build ?
[/quote]

Yes

SGaist

Ok, then what does the debugger tell you ?