Which approach is better use of HttpClient in .NET Framework 4.7?

Question

Which approach is the better use of HttpClient in .NET Framework 4.7?

In terms of socket exhaustion and thread safe? Both are reusing HttpClient instance, right?

I can't implement IHttpClientFactory right now. It is difficult to us to implement dependency injection

First code snippet:

class Program
{
    private static HttpClient httpClient;

    static void Main(string[] args)
    {
        httpClient = new HttpClient();
        httpClient.BaseAddress = new Uri("your base url");
        // add any default headers here also
        httpClient.Timeout = new TimeSpan(0, 2, 0); // 2 minute timeout

        MainAsync().Wait();
    }

    static async Task MainAsync()
    {
        await new MyClass(httpClient).StartAsync();
    }
}

public class MyClass
{
    private Dictionary<string, string> myDictionary;
    private readonly HttpClient httpClient;

    public MyClass(HttpClient httpClient)
    {
        this.httpClient = httpClient;
    }

    public async Task StartAsync()
    {
        myDictionary = await UploadAsync("some file path");
    }

    public async Task<Dictionary<string, string>> UploadAsync(string filePath)
    {
        byte[] fileContents;

        using (FileStream stream = File.Open(filePath, FileMode.Open))
        {
            fileContents = new byte[stream.Length];
            await stream.ReadAsync(fileContents, 0, (int)stream.Length);
        }

        HttpRequestMessage requestMessage = new HttpRequestMessage();
        // your request stuff here

        HttpResponseMessage httpResponse = await httpClient.SendAsync(requestMessage, HttpCompletionOption.ResponseContentRead, CancellationToken.None);

        // parse response and return the dictionary
    }
}

Second code snippet:

class Program
{
    static void Main(string[] args)
    {
        MainAsync().Wait();
    }

    static async Task MainAsync()
    {
        await new MyClass().StartAsync();
    }
}

public class MyClass
{
    private Dictionary<string, string> myDictionary;
    private static readonly HttpClient httpClient= = new HttpClient() { BaseAddress = new Uri("your base url"), Timeout = new TimeSpan(0, 2, 0) };

    public async Task StartAsync()
    {
        myDictionary = await UploadAsync("some file path");
    }

    public async Task<Dictionary<string, string>> UploadAsync(string filePath)
    {
        byte[] fileContents;

        using (FileStream stream = File.Open(filePath, FileMode.Open))
        {
            fileContents = new byte[stream.Length];
            await stream.ReadAsync(fileContents, 0, (int)stream.Length);
        }

        HttpRequestMessage requestMessage = new HttpRequestMessage();
        // your request stuff here

        HttpResponseMessage httpResponse = await httpClient.SendAsync(requestMessage, HttpCompletionOption.ResponseContentRead, CancellationToken.None);

        // parse response and return the dictionary
    }
}

I'm expecting to resolve socket exhaustion problem.