Closed
Description
Consider a scenario like the .NET 6 connection pool issue w.r.t. ConnectTimeout, here's the exception you'd see if you used HttpClient:
System.Threading.Tasks.TaskCanceledException: A task was canceled.
at System.Net.Http.HttpClient.HandleFailure(Exception e, Boolean telemetryStarted, HttpResponseMessage response, CancellationTokenSource cts, CancellationToken cancellationToken, CancellationTokenSource pendingRequestsCts)
at System.Net.Http.HttpClient.<SendAsync>g__Core|83_0(HttpRequestMessage request, HttpCompletionOption completionOption, CancellationTokenSource cts, Boolean disposeCts, CancellationTokenSource pendingRequestsCts, CancellationToken originalCancellationToken)
and if you used HttpMessageInvoker instead:
System.Threading.Tasks.TaskCanceledException: A task was canceled.
at System.Threading.Tasks.TaskCompletionSourceWithCancellation`1.WaitWithCancellationAsync(CancellationToken cancellationToken)
at System.Net.Http.HttpConnectionPool.HttpConnectionWaiter`1.WaitForConnectionAsync(Boolean async, CancellationToken requestCancellationToken)
at System.Net.Http.HttpConnectionPool.SendWithVersionDetectionAndRetryAsync(HttpRequestMessage request, Boolean async, Boolean doRequestAuth, CancellationToken cancellationToken)
at System.Net.Http.RedirectHandler.SendAsync(HttpRequestMessage request, Boolean async, CancellationToken cancellationToken)
and a similar example in .NET 5:
System.Threading.Tasks.TaskCanceledException: The operation was canceled.
at System.Net.Http.ConnectHelper.ConnectAsync(Func`3 callback, DnsEndPoint endPoint, HttpRequestMessage requestMessage, CancellationToken cancellationToken)
at System.Net.Http.HttpConnectionPool.ConnectAsync(HttpRequestMessage request, Boolean async, CancellationToken cancellationToken)
at System.Net.Http.HttpConnectionPool.CreateHttp11ConnectionAsync(HttpRequestMessage request, Boolean async, CancellationToken cancellationToken)
at System.Net.Http.HttpConnectionPool.GetHttpConnectionAsync(HttpRequestMessage request, Boolean async, CancellationToken cancellationToken)
at System.Net.Http.HttpConnectionPool.SendWithRetryAsync(HttpRequestMessage request, Boolean async, Boolean doRequestAuth, CancellationToken cancellationToken)
at System.Net.Http.RedirectHandler.SendAsync(HttpRequestMessage request, Boolean async, CancellationToken cancellationToken)
at System.Net.Http.HttpClient.SendAsyncCore(HttpRequestMessage request, HttpCompletionOption completionOption, Boolean async, Boolean emitTelemetryStartStop, CancellationToken cancellationToken)
Part of the reason is that in HttpClient.HadleFailure, we're only capturing the InnerException in some cases
In the above example,
oce.InnerException is null, and oce itself contains the useful stack trace.
And in this edge case we're throwing away the original exception entirely