Tag Archives: Fail

ML.Net YoloV5 + Security Camera “async” fail

Posted on by

While debugging my AzureIoTSmartEdgeCamera application I kept on getting file locked errors when the image from the security camera downloading which was a bit odd. So, I went back to basics and started with only the compiler directives required to build a “minimalist” version of the application.

Console output of minimalist application

If I had been paying attention, I would have noticed the issue here. I had missed that in the first block of System.Console.Writelines that the image download finished after the YoloV5 inferencing started.

#if CAMERA_SECURITY
private void SecurityCameraImageCapture()
{
	_logger.LogTrace("Security Camera Image download start");

	NetworkCredential networkCredential = new NetworkCredential()
	{
		UserName = _securityCameraSettings.CameraUserName,
		Password = _securityCameraSettings.CameraUserPassword,
	};

	using (WebClient client = new WebClient())
	{
		client.Credentials = networkCredential;

		client.DownloadFile(_securityCameraSettings.CameraUrl, _applicationSettings.ImageCameraFilepath);
	}

	_logger.LogTrace("Security Camera Image download done");
}
#endif

I had replaced the System.Net.WebClient(deprecated) image download implementation with code that retrieved images from the security camera using System.Net.Http.HttpClient.

#if CAMERA_SECURITY
      private async Task SecurityCameraImageCapture()
      {
         _logger.LogTrace("Security Camera Image download start");

         using (Stream cameraStream = await _httpClient.GetStreamAsync(_securityCameraSettings.CameraUrl))
         using (Stream fileStream = File.Create(_applicationSettings.ImageCameraFilepath))
         {
            await cameraStream.CopyToAsync(fileStream);
         }

         _logger.LogTrace("Security Camera Image download done");
      }
#endif

If I had been paying attention, I would have also noticed the issue here..

Console output of maximalist application

When I changed the compiler definitions to turn on pretty much every feature the issue became really really obvious because the “Security Camera Image download done” message wasn’t displayed.

#if CAMERA_RASPBERRY_PI
				RaspberryPIImageCapture();
#endif
#if CAMERA_SECURITY
				SecurityCameraImageCapture();
#endif

The original code to get the image from the camera was synchronous and I had forgotten to add an await.

#if CAMERA_RASPBERRY_PI
			RaspberryPIImageCapture();
#endif
#if CAMERA_SECURITY
            await SecurityCameraImageCaptureAsync();
#endif

I then updated the code and the application worked as expected.

Console output of working maximalist application

Summary

Would have saved myself a lot of time if I had paid attention to the debugging information and compiler warnings.