并行编程卡在串行设备的 Concurrency::create_task 调用的第四个实例上

我目前正在开发一个程序，其中Raspberry Pi 3将每隔100ms读取4个Arduino（USB）设备通过串行通信发送的内容。 UI 在 Concurrency::create_task 的第四次调用 (serialDeviceIndex = 3) 上卡住，但如果只有 3 个 Arduino 设备，则问题不会发生，线程执行继续到 .then lambda 主体。你能帮我找出问题所在吗？这是当connect按下 xaml 设备中的按钮。

void MainPage::comPortInput_Click(Object^ sender, RoutedEventArgs^ e)
{   
m_timer->Start();
auto selectionIndex = ConnectDevices->SelectedIndex;

if (selectionIndex < 0)
{
    status->Text = "Select a device and connect";
    return;
}

auto selectedItems = ConnectDevices->SelectedItems;

for (unsigned serialDeviceIndex = 0; serialDeviceIndex < selectedItems->Size; serialDeviceIndex++)
{
        Device ^device = static_cast<Device ^>(selectedItems->GetAt(serialDeviceIndex));
        textBox->Text = textBox->Text + "\n<START>:" + device->Id->ToString() + "<END>";
        Windows::Devices::SerialCommunication::SerialDevice ^serial_device;
        Windows::Devices::Enumeration::DeviceInformation ^entry = device->DeviceInfo;

        auto childTokenSource = Concurrency::cancellation_token_source::create_linked_source(cancellationTokenSource->get_token());

        auto childToken = childTokenSource.get_token();

        Concurrency::create_task(
            Windows::Devices::SerialCommunication::SerialDevice::FromIdAsync(entry->Id), childToken)
            .then([this, serialDeviceIndex](Windows::Devices::SerialCommunication::SerialDevice ^serial_device)
        {
            _serialPort = serial_device;
            Platform::String ^deviceString1 = _serialPort->ToString();
            // Disable the 'Connect' button 
            //comPortInput->IsEnabled = false;
            Windows::Foundation::TimeSpan _timeOut;
            _timeOut.Duration = 100000L; //100000 works with delay(200)

            // Configure serial settings
            _serialPort->WriteTimeout = _timeOut;

            _serialPort->ReadTimeout = _timeOut;
            _serialPort->BaudRate = 9600;
            _serialPort->Parity = Windows::Devices::SerialCommunication::SerialParity::None;
            _serialPort->StopBits = Windows::Devices::SerialCommunication::SerialStopBitCount::One;
            _serialPort->DataBits = 8;
            _serialPort->Handshake = Windows::Devices::SerialCommunication::SerialHandshake::None;

            _dataReaderObject = ref new Windows::Storage::Streams::DataReader(_serialPort->InputStream);
            _dataReaderObject->InputStreamOptions = Windows::Storage::Streams::InputStreamOptions::Partial;

            _dataReaderObjects.Append(_dataReaderObject);
            _serialPorts.Append(_serialPort);
            int serialPortsSize = _serialPorts.Size;
            Listen(_serialPorts.GetAt(serialDeviceIndex), _dataReaderObject, serialDeviceIndex);
        });
    Sleep(5);
}

}

EDIT:

好的，我现在将代码简化为这个

for (unsigned serialDeviceIndex = 0; serialDeviceIndex < selectedItems->Size; serialDeviceIndex++){
    Device ^device = static_cast<Device ^>(selectedItems->GetAt(serialDeviceIndex));
    textBox->Text = textBox->Text + "\n<START>:" + device->Id->ToString() + "<END>";
    Windows::Devices::Enumeration::DeviceInformation ^entry = device->DeviceInfo;
    auto it = Concurrency::create_task(Windows::Devices::SerialCommunication::SerialDevice::FromIdAsync(entry->Id));

    while (!it.is_done())
        textBoxStatus->Text = "processing" + deviceIndex.ToString();

    it.get();
}

仅供参考，这段代码在我的电脑上运行正常。没有错误。当我尝试在 Windows IoT 下的 RaspberryPi3 中运行此程序时，我第四次尝试使用该设备时程序挂起it.get()