[Qt-interest] QUdp sockets stops receiving after a while

[David Boosalis]

Thank you for the reply,  I'll try to create a stand along application that
reproduces the bug, but for now here is part of my code.

The UDP socket binds to the port 4005, in the thread's run methods.   I bind
with the option QUdpSocket::ReuseAddressHint, but it does not matter if I
use it or not.

If you see anything below that looks bad, please let me know.  Thank you
very much.



/***********************************************************************/
void NetworkThread::processPendingDatagramsSlot()
{
  static int count =0;  // see how long it runs for
  uint j;
  QString message;
  quint32 qui;
  qint32 modelID;

  UserMessage::Type mt;
  QList <QByteArray> *history;
  QByteArray  historyData;
  QByteArray datagram;

  qDebug() << "Process pending datagram, count  = " << count++;


  qint64 size = 0;
  //while(dataSocket->hasPendingDatagrams()) {
  // commented out this while loop as I thought it might be getting
  // in some infinte loop.
  datagram.resize(dataSocket->pendingDatagramSize());

  size += dataSocket->readDatagram(datagram.data(),datagram.size());
  qDebug() << "\tread in =" << size << "dg size = " << datagram.size();
  // size & dg size are always the same
  // }

  QDataStream in(&datagram,QIODevice::ReadOnly);
  QByteArray block;


  in >> dataBlockSize;
  in >> qui;

  mt = (UserMessage::Type) qui;

  if (mt ==  UserMessage::HistoricalData) {
    qDebug() << "Have history...." << __FILE__;
    in >> historyData;
    if (historyData.size() < 1)
      return;
    qDebug() << "*************************************";
    qDebug() << "Historical data , size = " << historyData.size();

    QDataStream historyStream(&historyData, QIODevice::ReadOnly);
    historyStream >> modelID;
    history = new QList<QByteArray>();

    historyStream >> *history;
    qDebug() << "Num of history items = " << history->count();
    if (history->count() < 1) {
      blockSize = 0;
      return;
    }

    emit setHistory(modelID,history);

  }

  else if (mt == UserMessage::ModelTickerUpdate) {
    // qDebug() << "Have ticker update....";
    processTickerData(in);
// in the same thread it parses the incoming data , creates a new
// Data class which sends a signal to the GUI thread that reads the
// data, and deletes the Data class
  }

 ...

  else  {
    qDebug() << "Unknown messge type in prcess pending datagram..." << mt;

    }
  }
}


On Thu, Feb 25, 2010 at 1:38 AM, Markus Goetz <Markus.Goetz at nokia.com>wrote:

> ext David Boosalis wrote:
>
>> I have a QUdpSocket that gets data just fine for quite some time, the data
>> is coming in fairly fast at every 100 miliseconds over the internet.  But
>> then after receiving a lot of messages (Sometimes a lot is 4,000 messages,
>> sometimes it is over 8000 messages) it just stops receiving all messages.
>>
>> The server acts as the client and connects to the client for sending UPD
>> sockets.  The server (I mean the client) still thinks it is connected and
>> sends data on its UdpSocket.  It's QUdpSocket::state also reports that it is
>> connected.   The problem is on Windows and Linux
>>
>> Does anyone have any insite as to why a QUdpSocket might stop after
>> working fine for some time.  Should I periodically close the port used for
>> binding and reopen it.
>> .
>>
> No, but can you send a minimal example that reproduces the problem?
>
> I can't think of a reason this happens.
>
> Markus
>
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