Data loss in receiving and writing big data using UDP and fprintf

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C++

MFC

file

UDP

Hello

My program receives data from UDP (a packet of 414 byte data at a time, 400 times/sec)

and writes the received data (414 bytes) into a text file using fprintf()

and writes part of the data into image files using fprintf().

In a threaded function, the UDP communication and file write look like:

while(1)
    {
        // Block until receive message from a client
        int recvMsgSize = udpServer.ReceiveFrom(buffer, UDP_DATA_MAX, senderIP, senderPort);

        if (recvMsgSize < 0)
        {
            AfxMessageBox("Receive failed");
        }

        buffer[recvMsgSize]='\0';

        if (dlg->m_log_running)
        {
            dlg_setting->WriteSerial(buffer, recvMsgSize);

            Decode_Image(buffer);
            Decode_NavData(buffer);
        }

        stringToHexa_WiresharkForm(buffer, recvMsgSize, buffer_hex);

        if (dlg->m_dataPrintType == 0) // print
            dlg->m_udpReceive.SetWindowTextA(buffer_hex);
        else // hide
            ;

        if (dlg->m_log_running)
            fprintf(ptr_logFile, "%s\n\n", buffer_hex);
    }

For small data, it works well.

But repeatedly there is data loss after receiving about 8 MB of data.

Both of the image files (also using fprintf() ) and the text file have lost data.

While, the data captured by WireShark has no lost data..


The problem would be in UDP receive or fprintf().

Is it a memory-related problem? I'd like to understand how it occurred.

Thank you for any advises..!