4. QSocketNotifier: Socket notifiers cannot be enabled or disabled from another thread

QSocketNotifier: Socket notifiers cannot be enabled or disabled from another thread


  • hi.
    excuse me. I am weak in English.
    I'm trying to write a program that reads UDP datagrams with separate thread.

    class NetRecieverThread : public QThread
{
    Q_OBJECT
public:
    QUdpSocket *m_Socket;
    int m_iPortNum;
    QString m_stIpAddress;

    NetRecieverThread(QObject *parent ,QString  sAddress ,int PortNum )
    {
        m_iPortNum = PortNum;
        m_stIpAddress = sAddress;
        m_Socket = new QUdpSocket (this);
        bool bl = m_Socket ->bind(QHostAddress(sAddress),PortNum);
        bl = 0;

        //connect(m_Socket ,SIGNAL(readyRead()),this,SLOT(readData()));

    }

    void run() Q_DECL_OVERRIDE
    {
        while(true)
        {

            QByteArray datagram;
            bool ReadyRead = false;
            while(!ReadyRead)
                ReadyRead = m_Socket->waitForReadyRead(30000);

            datagram.resize(m_Socket->pendingDatagramSize());

            QHostAddress sender;
            quint16 senderPort;


           int iSize =  m_Socket->readDatagram(datagram.data(),datagram.size(),&sender,&senderPort);
           if(iSize <=0)
               return;


            char *data = datagram.data();
             quint8 RecData = data[0];
             qDebug() <<"\n \n\ NetRecieverThread : Rec Data "<<RecData<<"Thread Information : "<< QThread::currentThread()<<QThread::currentThreadId();
            emit resultReady(datagram);

        }
    }
signals:
    void resultReady(QByteArray datagram);

};

//--------------------------------------------------------------------
//--------------------------------------------------------------------

class NetRecieveManager : public QObject
{
    Q_OBJECT
     NetRecieverThread *tRec;
public:
    NetRecieveManager()
    {
    }



    void startWorkInAThread()
    {

       tRec = new NetRecieverThread(0,"127.0.0.1",56071);
       connect(tRec, &NetRecieverThread::resultReady, this, &NetRecieveManager::handleResults);

      tRec->start();

    }
private slots:
    void handleResults(QByteArray datagram)
    {
       char *ch  = datagram.data();
       quint8 RecData = ch[0];
       qDebug() <<"NetRecieveManager: Rec Data "<<RecData<<"Thread Information : "<< QThread::currentThread()<<QThread::currentThreadId()<<"\n \n ";

    }

};

//--------------------------------------------------------------------
//--------------------------------------------------------------------
int main(int argc, char *argv[])
{
    QApplication a(argc, argv);

    //------------------------------------------------------
    NetRecieveManager myob;
    QThread  NetMangerThread;
    NetMangerThread.setObjectName("NetMangerThread");

    myob.startWorkInAThread();
    myob.moveToThread(&NetMangerThread);
    NetMangerThread.start();
    //------------------------------------------------------

    return a.exec();
}

    then output program is :

     QSocketNotifier: Socket notifiers cannot be enabled or disabled from another thread
QSocketNotifier: Socket notifiers cannot be enabled or disabled from another thread
QSocketNotifier: Socket notifiers cannot be enabled or disabled from another thread
QSocketNotifier: Socket notifiers cannot be enabled or disabled from another thread

 
 NetRecieverThread : Rec Data  208 Thread Information :  NetRecieverThread(0xb625c8) 0xe10
NetRecieveManager: Rec Data  208 Thread Information :  QThread(0x12fedc, name = "NetMangerThread") 0xb38 
 
 
QSocketNotifier: Socket notifiers cannot be enabled or disabled from another thread

 
 NetRecieverThread : Rec Data  209 Thread Information :  NetRecieverThread(0xb625c8) 0xe10
QSocketNotifier: Socket notifiers cannot be enabled or disabled from another thread
NetRecieveManager: Rec Data  209 Thread Information :  QThread(0x12fedc, name = "NetMangerThread") 0xb38 
 
 
QSocketNotifier: Socket notifiers cannot be enabled or disabled from another thread
QSocketNotifier: Socket notifiers cannot be enabled or disabled from another thread
QSocketNotifier: Socket notifiers cannot be enabled or disabled from another thread

 
 NetRecieverThread : Rec Data  210 Thread Information :  NetRecieverThread(0xb625c8) 0xe10
QSocketNotifier: Socket notifiers cannot be enabled or disabled from another thread
NetRecieveManager: Rec Data  210 Thread Information :  QThread(0x12fedc, name = "NetMangerThread") 0xb38 
 
 
QSocketNotifier: Socket notifiers cannot be enabled or disabled from another thread
QSocketNotifier: Socket notifiers cannot be enabled or disabled from another thread
QSocketNotifier: Socket notifiers cannot be enabled or disabled from another thread

 
 NetRecieverThread : Rec Data  211 Thread Information :  NetRecieverThread(0xb625c8) 0xe10
QSocketNotifier: Socket notifiers cannot be enabled or disabled from another thread
NetRecieveManager: Rec Data  211 Thread Information :  QThread(0x12fedc, name = "NetMangerThread") 0xb38 
 
 
QSocketNotifier: Socket notifiers cannot be enabled or disabled from another thread
QSocketNotifier: Socket notifiers cannot be enabled or disabled from another thread
QSocketNotifier: Socket notifiers cannot be enabled or disabled from another thread

 
 NetRecieverThread : Rec Data  212 Thread Information :  NetRecieverThread(0xb625c8) 0xe10
QSocketNotifier: Socket notifiers cannot be enabled or disabled from another thread
NetRecieveManager: Rec Data  212 Thread Information :  QThread(0x12fedc, name = "NetMangerThread") 0xb38

    everything is ok. both 2 threads work good. i dont know why get this message
    QSocketNotifier: Socket notifiers cannot be enabled or disabled from another thread

    Is the problem will be.
    thanks

    0
  • Lifetime Qt Champion

    Hi and welcome to devnet,

    The constructor of NetRecieverThread is run in the main thread so m_Socket is created in the main thread. On the other hand the run method is called in the thread managed by QThread that's why you get the message.

    0 2 Replies

  • This post is deleted!
    0

  • @SGaist
    thanks SGait
    ok.
    i change code and move create m_socket to run function and solved problem.

        void run() Q_DECL_OVERRIDE
    {
        m_Socket = new QUdpSocket (0);
        bool bl = m_Socket ->bind(QHostAddress(m_stIpAddress),m_iPortNum);
     while(true)
     {
       .
       .
       .
    0
  • Lifetime Qt Champion

    Don't forget to delete the socket before the end of run otherwise you'll have a memory leak

    0
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