Memory leak when creating many ImageAnnotatorClient instances

Unsure what the root cause of the issue is but I noticed that creating a lot of ImageAnnotatorClient instances causes a consistent rise in unmanaged memory (first guess is - it’s creating a lot of HttpClients):

I was initialising a ImageAnnotatorClient per image and I am sending 50-100 images per second so I was quite quickly running out of memory. Now, I just reuse the same ImageAnnotatorClient for each batch of images and I now see fairly consistent memory usage (sorry for the differing pictures, the bottom graph shows the unmanaged memory - and it’s basically flatlined):

I was just wondering whether:

1. It’s okay to reuse the client, several hundred times?
2. Whether I’ve exposed a bug (maybe something isn’t being GC’d?)…

Is this possibly a duplicate/symptom of this issue or perhaps this issue

These are my installed packages:

  <package id="Google.Api.CommonProtos" version="1.2.0" targetFramework="net46" />
  <package id="Google.Api.Gax" version="2.2.1" targetFramework="net46" />
  <package id="Google.Api.Gax.Grpc" version="2.2.1" targetFramework="net46" />
  <package id="Google.Apis" version="1.32.2" targetFramework="net46" />
  <package id="Google.Apis.Auth" version="1.32.2" targetFramework="net46" />
  <package id="Google.Apis.Core" version="1.32.2" targetFramework="net46" />
  <package id="Google.Cloud.Vision.V1" version="1.1.0" targetFramework="net46" />
  <package id="Google.Protobuf" version="3.5.1" targetFramework="net46" />
  <package id="Grpc.Auth" version="1.10.0" targetFramework="net46" />
  <package id="Grpc.Core" version="1.10.0" targetFramework="net46" />

[markwalsh-liverpool]

Okay, great that makes perfect sense. In case anyone else is reading and finds they have the same problem I modified my code to be:

        private static ImageAnnotatorClient _client;
        public ImageAnnotatorClient Create()
        {
            if (_client == null)
            {
                var credential = GoogleCredential
                    .FromFile(AppDomain.CurrentDomain.BaseDirectory + "google-cloud-vision-license.json")
                    .CreateScoped(ImageAnnotatorClient.DefaultScopes);
                var channel = new Channel(ImageAnnotatorClient.DefaultEndpoint.ToString(),
                    credential.ToChannelCredentials());
                _client = ImageAnnotatorClient.Create(channel);
            }

            return _client;
        }

Thanks Jon!

[evildour]

Note that if you’re using this from multiple threads, you may want to use Lazy<T> instead:

private static readonly Lazy<ImageAnnotatorClient> _client = new Lazy<ImageAnnotatorClient>(() => {
    var credential = GoogleCredential
        .FromFile(AppDomain.CurrentDomain.BaseDirectory + "google-cloud-vision-license.json")
        .CreateScoped(ImageAnnotatorClient.DefaultScopes);
    var channel = new Channel(ImageAnnotatorClient.DefaultEndpoint.ToString(),
        credential.ToChannelCredentials());
    return ImageAnnotatorClient.Create(channel);
});