QLocalSocket::readyRead() signal does not work as expected

The communication between two processes via QLocalSocket breaks after some time. It seems to be a regression bug because the code works fine with Qt4.8.4.
The Test-Setup is attached as QtCreator project.

Test-Setup:

1. A server process that starts a QLocalServer
2. A client process that connects to the server and tries to write continously a message (in our case just 6 bytes, 2 bytes as size information of type quint16 and 4 bytes as running number of type qint32)
3. When the client is connected to the server...
   • ...the client sends messages to the server and writes via qDebug() the message count whenever 1000 messages are sent, additionally the client sleeps every 1000 messages for a duration of 500ms.
   • ...the server receives the client messages, checks the running number (previous number = current number - 1) and writes via qDebug() the running number or stops if an error occurs.

Steps to reproduce:

1. Start the server
2. Start the client

Result

After some time it seems as if some bytes will be lost so that the running number check will fail. Usually, the effect takes place in less than 60 seconds. You can increase the chance by increasing the CPU usage, for example by opening a browser. Another way could be to increase the byte count of the messages.

Code

Here is the function that is connected to the readyRead() signal of class QLocalSocket. _previousNumber is a member variable of class Socket

void Socket::read()
{
    while (!_socket->atEnd())
    {
        // check that at least 2 bytes are available
        if (_socket->bytesAvailable() < 2)
            return;

        // read these two bytes
        QDataStream sizeStream(_socket->read(2));

        // reinterpret these two bytes as size information of type quint16
        quint16 dataCount(0);
        sizeStream >> dataCount;

        // read more bytes as specified by 'dataCount'
        QDataStream dataStream(_socket->read(dataCount));

        // reinterpret data as qint32
        int currentNumber(0);
        dataStream >> currentNumber;

        qDebug() << currentNumber;

        // check running number
        if (_previousNumber != currentNumber - 1)
        {
            // stop listening
            qDebug() << ";-(";
            disconnect(_socket, SIGNAL(readyRead()), this, SLOT(read()));
            break;
        }

        _previousNumber = currentNumber;
    }
}

Again, this code works fine with Qt4.8.4. As workaround we avoid the readyRead() signal and poll the socket by a QTimer instead.