Improve cancellation handling for dotnet-stack

src/Microsoft.Diagnostics.NETCore.Client/DiagnosticsClient/EventPipeSession.cs

@@ -164,15 +164,8 @@ private bool TryCreateStopMessage(out IpcMessage stopMessage)
 
         protected virtual void Dispose(bool disposing)
         {
-            // If session being disposed hasn't been stopped, attempt to stop it first
-            if (!_stopped)
-            {
-                try
-                {
-                    Stop();
-                }
-                catch { } // swallow any exceptions that may be thrown from Stop.
-            }
+            // Do not call Stop() here. Trying to do so now might block indefinitely if the runtime is unresponsive and we don't want blocking behavior in Dispose().
+            // If the caller wants to ensure that all rundown events are captured they should call Stop() first, then process the EventStream until it is complete, then call Dispose().
 
             if (!_disposedValue)
             {

src/Tools/dotnet-stack/ReportCommand.cs

@@ -78,12 +78,13 @@ private static async Task<int> Report(CancellationToken ct, IConsole console, in
                 // is too short in a given environment, e.g., resource constrained systems
                 // N.B. - This trace INCLUDES rundown.  For sufficiently large applications, it may take non-trivial time to collect
                 //        the symbol data in rundown.
-                using (EventPipeSession session = client.StartEventPipeSession(providers))
+                EventPipeSession session = await client.StartEventPipeSessionAsync(providers, requestRundown:true, token:ct).ConfigureAwait(false);
+                using (session)
                 using (FileStream fs = File.OpenWrite(tempNetTraceFilename))
                 {
-                    Task copyTask = session.EventStream.CopyToAsync(fs);
-                    await Task.Delay(duration).ConfigureAwait(false);
-                    session.Stop();
+                    Task copyTask = session.EventStream.CopyToAsync(fs, ct);
+                    await Task.Delay(duration, ct).ConfigureAwait(false);
+                    await session.StopAsync(ct).ConfigureAwait(false);
 
                     // check if rundown is taking more than 5 seconds and add comment to report
                     Task timeoutTask = Task.Delay(TimeSpan.FromSeconds(5));
@@ -147,6 +148,10 @@ private static async Task<int> Report(CancellationToken ct, IConsole console, in
                     }
                 }
             }
+            catch (OperationCanceledException)
+            {
+                return -1;
+            }
             catch (Exception ex)
             {
                 Console.Error.WriteLine($"[ERROR] {ex}");