[Interest] Unknown crashes with Qt, iOS and iPad Air

Nuno Santos nunosantos at imaginando.pt
Mon Apr 20 10:36:48 CEST 2015


Robert,

Thanks for your reply.

> It's normally better to explain what your application
> is doing, which Qt modules it is using, QML or widgets, etc.,
> and which Qt versions and patches you are using.

My app is mostly a remote controller. It connect itself via QTcpSocket to a software utility on the host computer side and exchanges information with it. It has a lot of GUI and it’s currently memory hungry. I receive memory warnings easily and I still couldn’t find a way of lowering memory usage.

The version that is currently on the store is reporting crashes very similar to the one in the image attached. Since it is not in any point of my source code, I don’t have a clue of what it is. 

The place point before pointing to LK is the CFNetwork module. Could this indicate that the crash was caused during a network callback? 


> 
> Just the diff between recent iPad Air and old iPads
> could be loading of 2x images for Retina 2x displays
> versus 1x images for older iPads.
> Is your application memory hungry?
> Are you treating memory notification?

How am I supposed to treat memory notifications in Qt? One of the current problems is that i’m currently spending a lot of memory, specially due to Qml interfaces. How can I know how much a Qml element is spending memory? I couldn’t find that in Qml profiler yet.

> 
> Is there any clue from your users what is the trigger
> of the crashes reported?

Some of them say that is sufficient to open the app. Others say that it happens when they connect to the software utility on the host computer (which means, when the TCP socket communication is initiated)

I’m currently using a QTcpSocket moved to a thread. I’m not sure i’m doing it the right way. I was trying to optimize the thought put of the socket in order to avoid latency.

void LKSong::connectTo(QString name, QString address, int port)
{
    terminateConnection();

    _thread = new QThread(this);
    _connection = new LKConnection(QHostAddress(address),port);

    connect(_connection, SIGNAL(connected()), SLOT(connected()));
    connect(_connection, SIGNAL(disconnected()), SLOT(disconnected()));
    connect(_connection, SIGNAL(incomingData(QByteArray)), SLOT(incomingData(QByteArray)));

    connect(this, SIGNAL(sendToConnection(QByteArray)), _connection, SLOT(write(QByteArray)), Qt::QueuedConnection);

    _connection->moveToThread(_thread);
    connect(_thread, SIGNAL(started()), _connection, SLOT(started()));

    _thread->start(QThread::TimeCriticalPriority);

    _pendingConnectionBridgeName = name;
}

> 
> Look into symbolization of the crash reports if it could be helpful.

That’s the problem. I can’t find anything mean full.

> 
> Take care.
> Robert
> _______________________________________________
> Interest mailing list
> Interest at qt-project.org
> http://lists.qt-project.org/mailman/listinfo/interest

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