如何管理最大连接数，HttpClient，C＃？

Question

I'm working on a windows service. Code of windows service is very simple but it has a strange manner!
In windows service I should call a WebApi each 20 seconds and save the result in a SQL Database
I'm using autofac to creat instance of HttpClient at Program.cs

// HttpClient
builder.Register(ctx =>
{
    var httpClient = new HttpClient
    {
        BaseAddress = new Uri(StaticAssets.WebApiBaseAddress)
    };
    httpClient.DefaultRequestHeaders.Accept.Clear();
    httpClient.DefaultRequestHeaders.Accept.Add(new MediaTypeWithQualityHeaderValue("application/json"));
    return httpClient;
});

I never dispose httpClient instance manually.
After running the windows service about 8 hours, IIS not work and we can not remote to server anymore, we tested Windows Remote Desktop Connection, VNC(we have VNC on server) ...
We could remote to server with KVM and stop the windows service and every thing go back. I could find from here the problem is because of connection numbers! I'm not sure yet?
Also I found the following:

<system.web>
 <processModel maxWorkerThreads="100" maxIoThreads="100" minWorkerThreads="50"/>
 <httpRuntime minFreeThreads="704" minLocalRequestFreeThreads="608"/>
</system.web>

<system.net>
 <connectionManagement>
  <add address="[ProvideIPHere]" maxconnection="96"/>
 </connectionManagement>
</system.net>

From https://support.microsoft.com/en-us/help/821268/contention-poor-performance-and-deadlocks-when-you-make-calls-to-web-s

What is the best practice to manage max connections in HttpClient .Net windows service & IIS?

Answer 1

The solution base on googling:

1. Define HttpClient as SingleTone and don't dispose it manually.
In AutoFac use something like the following:

builder.Register(ctx =>
{
    var httpClient = new HttpClient
    {
        BaseAddress = new Uri('https://www.sample.com/')
    };
    httpClient.DefaultRequestHeaders.Accept.Clear();
    httpClient.DefaultRequestHeaders.Accept.Add(new MediaTypeWithQualityHeaderValue("application/json"));
    return httpClient;
}).SingleInstance();

In .Net Core use the following:

services.AddSingleton(provider =>
{
    var httpClient = new HttpClient
    {
        BaseAddress = new Uri('https://www.sample.com/')
    };
    httpClient.DefaultRequestHeaders.Accept.Clear();
    httpClient.DefaultRequestHeaders.Accept.Add(new MediaTypeWithQualityHeaderValue("application/json"));
    return httpClient;
});

2. Add the following in your config file

<configuration>
    ....
    <system.web>
     <processModel maxWorkerThreads="100" maxIoThreads="100" minWorkerThreads="50"/>
     <httpRuntime minFreeThreads="704" minLocalRequestFreeThreads="608"/>
    </system.web>

    <system.net>
     <connectionManagement>
      <add address="[ProvideIPHere]" maxconnection="96"/>
     </connectionManagement>
    </system.net>
</configuration>