Re-using HttpClient but with a different Timeout setting per request?

Question

In order to reuse open TCP connections with HttpClient you have to share a single instance for all requests.

This means that we cannot simply instantiate HttpClient with different settings (e.g. timeout or headers).

How can we share the connections and use different settings at the same time? This was very easy, in fact the default, with the older HttpWebRequest and WebClient infrastructure.

Note, that simply setting HttpClient.Timeout before making a request is not thread safe and would not work in a concurrent application (e.g. an ASP.NET web site).

Answer 1

Under the hood, HttpClient just uses a cancellation token to implement the timeout behavior. You can do the same directly if you want to vary it per request:

using var cts = new CancellationTokenSource(); cts.CancelAfter(TimeSpan.FromSeconds(30)); await httpClient.GetAsync("http://www.google.com", cts.Token); 

Note that the default timeout for HttpClient is 100 seconds, and the request will still be canceled at that point even if you've set a higher value at the request level. To fix this, set a "max" timeout on the HttpClient, which can be infinite:

httpClient.Timeout = System.Threading.Timeout.InfiniteTimeSpan;