IHttpClientFactory with Autofac in .NET 4.8

Question

I came to a point where I needed to replace usage of HttpClient with IHttpClientFactory in order to reduce number of sockets that are in use and avoid socket exhaustion.

As preferable approach, I wanted to use IHttpClientFactory and register it by using Autofac, and I also wanted to confirm the difference between usage of HttpClient and IHttpClientFactory - how to know if my implementation is working properly?

My base implementation of the class that uses IHttpClientFactory goes something like this (one of the classes):

public class ImportHttpClient : IImportHttpClientAccessor
    {
        public HttpClient Client { get; }

        public ImportHttpClient(IHttpClientFactory httpClientFactory)
        {
            ServicePointManager.SecurityProtocol = SecurityProtocolType.Tls12;
            Client = httpClientFactory.CreateClient();
            Client.BaseAddress = new Uri(GlobalVariables.ImportServiceSettings.BaseUrl);         
        }
    }

and registration of this class with Autofac is very straightforward:

builder.RegisterType<ImportHttpClient>().As<IImportHttpClientAccessor>().InstancePerLifetimeScope();

But, the registration of IHttpClientFactory remained the problem and also a test to compare before/after using IHttpClientFactory.

Answer 1

After a lot of research and checking out different resources, I managed to find a solution to my problems.

Registering IHttpClientFactory with Autofac in .NET 4.8 is done like this:

 builder.Register(ctx =>
            {
                var services = new ServiceCollection();
                services.AddHttpClient();
                var provider = services.BuildServiceProvider();
                return provider.GetRequiredService<IHttpClientFactory>();
            });

For testing HttpClient vs IHttpClientFactory I used netstat, and these are the results: With HttpClient (no HttpClientFactory):

as you can see there is a lot of open connections that are not automatically closed for a while.

Now, the same process, but with using IHttpClientFactory:

As you can see, instead of many connections that just "hang there", I got only several where connection is closed.