How do I configure timeouts for HttpClient (C#) requests?

In C#, HttpClient is a class provided by the System.Net.Http namespace used for sending HTTP requests and receiving HTTP responses. Sometimes, it's necessary to configure timeouts for HttpClient requests to ensure that your application does not hang indefinitely when a server is not responding.

The HttpClient class has a Timeout property that gets or sets the timespan to wait before the request times out. The timeout applies to the entire operation, including getting the connection, sending the request, and receiving the response.

Here's how you can configure the timeout for HttpClient requests:

using System;
using System.Net.Http;
using System.Threading.Tasks;

class Program
{
    static async Task Main()
    {
        using (var httpClient = new HttpClient())
        {
            // Set the timeout to 30 seconds
            httpClient.Timeout = TimeSpan.FromSeconds(30);

            try
            {
                // Make a request to the specified URI
                string requestUri = "https://example.com";
                HttpResponseMessage response = await httpClient.GetAsync(requestUri);

                // Ensure we got a successful response
                if (!response.IsSuccessStatusCode)
                {
                    Console.WriteLine($"Error: {response.StatusCode}");
                }
                else
                {
                    string responseBody = await response.Content.ReadAsStringAsync();
                    Console.WriteLine(responseBody);
                }
            }
            catch (TaskCanceledException ex)
            {
                // A TaskCanceledException will be thrown if the timeout period elapses
                // before the task completes. Note that HttpClient also throws this exception
                // if the request is canceled for other reasons, so you may want to check
                // the inner exception, if any, to determine the cause.
                if (ex.CancellationToken.IsCancellationRequested)
                {
                    Console.WriteLine("Request was canceled.");
                }
                else
                {
                    Console.WriteLine("Request timed out.");
                }
            }
            catch (Exception ex)
            {
                // Handle other exceptions that may occur
                Console.WriteLine($"Request failed: {ex.Message}");
            }
        }
    }
}

In this example, the Timeout property is set to 30 seconds. If the operation does not complete within this period, a TaskCanceledException is thrown, which you can catch and handle appropriately.

It’s important to note a couple of things about HttpClient and timeouts:

• The default value of the Timeout property is 100 seconds.
• Setting the Timeout property to TimeSpan.FromMilliseconds(Timeout.Infinite) will disable timeouts.
• The Timeout property applies to the entire operation from start to finish, including resolving DNS, establishing the connection, sending the request, and reading the response.
• If you need separate timeouts for the connection and the read operations, you would need to use HttpClientHandler or a similar approach to configure those timeouts on a lower-level class.

Remember, HttpClient is intended to be instantiated once and reused throughout the life of an application. Instantiating an HttpClient class for every request will exhaust the number of sockets available under heavy loads. This will result in SocketException errors.