google-cloud-dotnet: Grpc.Core.RpcException: Status(StatusCode=Unauthenticated, Detail="Deadline Exceeded") ?

At this point I suspect you really need a Datastore expert to help you. I’ll reach out internally to try to find someone who can help.

I’m afraid I don’t know details about Datastore itself - I work on a lot of different APIs, so don’t know very much about each of them. I just make sure you can get requests from C# code to the server…

Here’s a small sample for you for the pooling. You’d create an instance on start-up, then keep that instance everywhere, calling var db = pool.GetNextInstance(); each time you wanted to make a request. If you have a chance to test that out and see if it improves your latency, that would be really interesting.

using Google.Apis.Auth.OAuth2;
using Google.Cloud.Datastore.V1;
using Grpc.Auth;
using Grpc.Core;
using System.Linq;

namespace DatastoreTest
{
    // Sample code only; needs more work for productionization.

    /// <summary>
    /// Pool of DatastoreDb instances which are returned in round-robin order (they're never
    /// "returned" to the pool). Assumptions: default credentials, a single DB, and no need to
    /// release channels.
    /// </summary>
    public class RoundRobinDatastoreDbPool
    {
        private readonly DatastoreDb[] _instances;
        private int _nextIndex = 0;
        private readonly object _lock = new object();

        public RoundRobinDatastoreDbPool(string projectId, string namespaceId, int count)
        {
            var credentials = GoogleCredential.GetApplicationDefault()
                .CreateScoped(DatastoreClient.DefaultScopes) // Not necessary as of Grpc.Core 1.8
                .ToChannelCredentials();
            string host = DatastoreClient.DefaultEndpoint.Host;
            int port = DatastoreClient.DefaultEndpoint.Port;
            _instances = Enumerable.Range(0, count)
                .Select(_ => new Channel(host, port, credentials))
                .Select(channel => DatastoreClient.Create(channel))
                .Select(client => DatastoreDb.Create(projectId, namespaceId, client))
                .ToArray();
        }

        public DatastoreDb GetNextInstance()
        {
            lock (_lock)
            {
                DatastoreDb instance = _instances[_nextIndex++];
                if (_nextIndex == _instances.Length)
                {
                    _nextIndex = 0;
                }
                return instance;
            }
        }
    }
}