dont register shutdownhooks for dotnet5.4

src/csharp/Grpc.Core.Tests/AppDomainUnloadTest.cs

@@ -32,13 +32,7 @@
 #endregion
 
 using System;
-using System.Diagnostics;
-using System.Linq;
-using System.Reflection;
-using System.Threading;
 using System.Threading.Tasks;
-using Grpc.Core;
-using Grpc.Core.Internal;
 using Grpc.Core.Utils;
 using NUnit.Framework;
 
@@ -46,6 +40,13 @@ namespace Grpc.Core.Tests
 {
     public class AppDomainUnloadTest
     {
+#if DOTNET5_4
+        [Test]
+        [Ignore("Not supported for CoreCLR")]
+        public void AppDomainUnloadHookCanCleanupAbandonedCall()
+        {
+        }
+#else
         [Test]
         public void AppDomainUnloadHookCanCleanupAbandonedCall()
         {
@@ -86,5 +87,6 @@ namespace Grpc.Core.Tests
                 readyToShutdown.Task.Wait();  // make sure handler is running
             }
         }
+#endif
     }
 }

src/csharp/Grpc.Core/GrpcEnvironment.cs

@@ -352,8 +352,12 @@ namespace Grpc.Core
                 {
                     if (!hooksRegistered)
                     {
+                        // TODO(jtattermusch): register shutdownhooks for CoreCLR as well
+#if !DOTNET5_4
+
                         AppDomain.CurrentDomain.ProcessExit += ShutdownHookHandler;
                         AppDomain.CurrentDomain.DomainUnload += ShutdownHookHandler;
+#endif
                     }
                     hooksRegistered = true;
                 }