fix C# connectivity watcher shutdown race

1 files changed, 12 insertions, 2 deletions

diff --git a/src/csharp/Grpc.Core/Channel.cs b/src/csharp/Grpc.Core/Channel.cs
index e7b30cd1e9..d4fcd1ad9c 100644
--- a/src/csharp/Grpc.Core/Channel.cs
+++ b/src/csharp/Grpc.Core/Channel.cs
@@ -160,8 +160,18 @@ namespace Grpc.Core
             var deadlineTimespec = deadline.HasValue ? Timespec.FromDateTime(deadline.Value) : Timespec.InfFuture;
             lock (myLock)
             {
-                // pass "tcs" as "state" for WatchConnectivityStateHandler.
-                handle.WatchConnectivityState(lastObservedState, deadlineTimespec, completionQueue, WatchConnectivityStateHandler, tcs);
+                if (handle.IsClosed)
+                {
+                    // If channel has been already shutdown and handle was disposed, we would end up with
+                    // an abandoned completion added to the completion registry. So we act as if the
+                    // wait has timed out instead.
+                    tcs.SetResult(false);
+                }
+                else
+                {
+                    // pass "tcs" as "state" for WatchConnectivityStateHandler.
+                    handle.WatchConnectivityState(lastObservedState, deadlineTimespec, completionQueue, WatchConnectivityStateHandler, tcs);
+                }
             }
             return tcs.Task;
         }