Do HttpClient and HttpClientHandler have to be disposed between requests?

Question

System.Net.Http.HttpClient and System.Net.Http.HttpClientHandler in .NET Framework 4.5 implement IDisposable (via System.Net.Http.HttpMessageInvoker).

The usin

Answer 1

Dispose() calls the code below, which closes the connections opened by the HttpClient instance. The code was created by decompiling with dotPeek.

HttpClientHandler.cs - Dispose

ServicePointManager.CloseConnectionGroups(this.connectionGroupName);

If you don't call dispose then ServicePointManager.MaxServicePointIdleTime, which runs by a timer, will close the http connections. The default is 100 seconds.

ServicePointManager.cs

internal static readonly TimerThread.Callback s_IdleServicePointTimeoutDelegate = new TimerThread.Callback(ServicePointManager.IdleServicePointTimeoutCallback);
private static volatile TimerThread.Queue s_ServicePointIdlingQueue = TimerThread.GetOrCreateQueue(100000);

private static void IdleServicePointTimeoutCallback(TimerThread.Timer timer, int timeNoticed, object context)
{
  ServicePoint servicePoint = (ServicePoint) context;
  if (Logging.On)
    Logging.PrintInfo(Logging.Web, SR.GetString("net_log_closed_idle", (object) "ServicePoint", (object) servicePoint.GetHashCode()));
  lock (ServicePointManager.s_ServicePointTable)
    ServicePointManager.s_ServicePointTable.Remove((object) servicePoint.LookupString);
  servicePoint.ReleaseAllConnectionGroups();
}

If you haven't set the idle time to infinite then it appears safe not to call dispose and let the idle connection timer kick-in and close the connections for you, although it would be better for you to call dispose in a using statement if you know you are done with an HttpClient instance and free up the resources faster.