Do not raise events from language worker channel when disposing (#4468)

Author: pragnagopa

src/WebJobs.Script/Rpc/FunctionRegistration/FunctionDispatcher.cs

@@ -263,15 +263,12 @@ private void AddOrUpdateWorkerChannels(RpcJobHostChannelReadyEvent rpcChannelRea
 
         protected virtual void Dispose(bool disposing)
         {
-            if (!_disposed)
+            if (!_disposed && disposing)
             {
-                if (disposing)
-                {
-                    _workerErrorSubscription.Dispose();
-                    _rpcChannelReadySubscriptions.Dispose();
-                    _workerState.DisposeAndRemoveChannels();
-                    _workerState.Functions.Dispose();
-                }
+                _workerErrorSubscription.Dispose();
+                _rpcChannelReadySubscriptions.Dispose();
+                _workerState.DisposeAndRemoveChannels();
+                _workerState.Functions.Dispose();
                 _disposed = true;
             }
         }

src/WebJobs.Script/Rpc/LanguageWorkerChannel.cs

@@ -284,6 +284,11 @@ internal void SendWorkerInitRequest(RpcEvent startEvent)
 
         internal void PublishWorkerProcessReadyEvent(FunctionEnvironmentReloadResponse res)
         {
+            if (_disposing)
+            {
+                // do not publish ready events when disposing
+                return;
+            }
             WorkerProcessReadyEvent wpEvent = new WorkerProcessReadyEvent(_workerId, _workerConfig.Language);
             _eventManager.Publish(wpEvent);
         }
@@ -293,6 +298,11 @@ internal void PublishRpcChannelReadyEvent(RpcEvent initEvent)
             _startLatencyMetric?.Dispose();
             _startLatencyMetric = null;
 
+            if (_disposing)
+            {
+                // do not publish ready events when disposing
+                return;
+            }
             _initMessage = initEvent.Message.WorkerInitResponse;
             if (_initMessage.Result.IsFailure(out Exception exc))
             {
@@ -494,6 +504,10 @@ internal void Log(RpcEvent msg)
 
         internal void HandleWorkerError(Exception exc)
         {
+            if (_disposing)
+            {
+                return;
+            }
             LanguageWorkerProcessExitException langExc = exc as LanguageWorkerProcessExitException;
             // The subscriber of WorkerErrorEvent is expected to Dispose() the errored channel
             if (langExc != null && langExc.ExitCode == -1)

src/WebJobs.Script/Rpc/LanguageWorkerState.cs

@@ -37,9 +37,11 @@ internal void DisposeAndRemoveChannels()
         {
             foreach (string channelId in _channels.Keys)
             {
-                _channels[channelId].Dispose();
+                if (_channels.TryRemove(channelId, out ILanguageWorkerChannel channel))
+                {
+                    channel?.Dispose();
+                }
             }
-            _channels.Clear();
         }
 
         internal IEnumerable<ILanguageWorkerChannel> GetChannels()